Dicing tape-integrated film for semiconductor back surface

ABSTRACT

The present invention provides a dicing tape-integrated film for semiconductor back surface, including: a dicing tape including a base material and a pressure-sensitive adhesive layer provided on the base material; and a film for flip chip type semiconductor back surface provided on the pressure-sensitive adhesive layer, in which the film for flip chip type semiconductor back surface has a storage elastic modulus (at 60° C.) of from 0.9 MPa to 15 MPa.

FIELD OF THE INVENTION

The present invention relates to a dicing tape-integrated film forsemiconductor back surface which includes a film for flip chip typesemiconductor back surface. The film for flip chip type semiconductorback surface is used for the purposes of protecting a back surface of achip-shaped workpiece (such as a semiconductor chip) and enhancingstrength and the like. Also, the invention relates to a process forproducing a semiconductor device using a dicing tape-integrated film forsemiconductor back surface and a flip chip-mounted semiconductor device.

BACKGROUND OF THE INVENTION

In recent years, thinning and miniaturization of a semiconductor deviceand its package have been increasingly demanded. Therefore, as thesemiconductor device and its package, semiconductor devices of a flipchip type in which a chip-shaped workpiece such as a semiconductor chipis mounted (flip chip-bonded) on a substrate by means of flip chipbonding have been widely utilized. In such flip chip bonding, asemiconductor chip is fixed to a substrate in a form where a circuitface of the semiconductor chip is opposed to an electrode-formed face ofthe substrate. In such a semiconductor device or the like, there may bea case where the back surface of the semiconductor chip (chip-shapedworkpiece) is protected with a protective film to inhibit thesemiconductor chip from damaging or the like (see, for example, PatentDocuments 1 to 10).

Patent Document 1: JP-A-2008-166451

Patent Document 2: JP-A-2008-006386

Patent Document 3: JP-A-2007-261035

Patent Document 4: JP-A-2007-250970

Patent Document 5: JP-A-2007-158026

Patent Document 6: JP-A-2004-221169

Patent Document 7: JP-A-2004-214288

Patent Document 8: JP-A-2004-142430

Patent Document 9: JP-A-2004-072108

Patent Document 10: JP-A-2004-063551

SUMMARY OF THE INVENTION

However, the attachment of a back surface protective film for protectinga back surface of a semiconductor chip to the back surface of thesemiconductor chip obtained by dicing a semiconductor wafer in a dicingstep results in the addition of a step for the attachment, so that thenumber of steps increases and cost and the like increase. Moreover,owing to the thinning, the semiconductor chip may be damaged in somecases in a picking-up step of the semiconductor chip after the dicingstep. Thus, it is desired to reinforce the semiconductor wafer orsemiconductor chip before the picking-up step.

In consideration of the foregoing problem, an object of the presentinvention is to provide a dicing tape-integrated film for semiconductorback surface capable of being utilized from the dicing step of thesemiconductor wafer to the flip chip bonding step of the semiconductorelement.

Moreover, another object of the invention is to provide a dicingtape-integrated film for semiconductor back surface capable ofexhibiting an excellent holding force in the dicing step of thesemiconductor wafer and capable of exhibiting an excellent markingproperty and an excellent appearance property after the flip chipconnecting step of the semiconductor element.

In order to solve the foregoing related-art problems, the presentinventors made extensive and intensive investigations. As a result, ithas been found that when a film for flip chip type semiconductor backsurface is laminated on a pressure-sensitive adhesive layer of a dicingtape having a base material and the pressure-sensitive adhesive layer soas to form the dicing tape and the film for flip chip type semiconductorback surface in an integrated form, and the film for flip chip typesemiconductor back surface is formed of a resin composition containing athermoplastic resin composition in a specified ratio, a laminate (dicingtape-integrated film for semiconductor back surface) in which the dicingtape and the film for flip chip type semiconductor back surface areformed in an integrated form can be utilized from a dicing step of asemiconductor wafer to a flip chip connection step of a semiconductorelement, an excellent holding force can be exhibited in the dicing stepof a semiconductor wafer, and an excellent marking property and anexcellent appearance property can be exhibited after the flip chipconnection step of a semiconductor element, leading to accomplishment ofthe invention.

Namely, the present invention provides a dicing tape-integrated film forsemiconductor back surface, comprising:

a dicing tape including a base material and a pressure-sensitiveadhesive layer provided on the base material; and

a film for flip chip type semiconductor back surface provided on thepressure-sensitive adhesive layer,

wherein the film for flip chip type semiconductor back surface has astorage elastic modulus (at 60° C.) of from 0.9 MPa to 15 MPa

As above, the dicing tape-integrated film for semiconductor back surfaceof the invention is formed in a form in which the film for flip chiptype semiconductor back surface is integrated with the dicing tapehaving the base material and the pressure-sensitive adhesive layer, andthe storage elastic modulus (at 60° C.) of the film for flip chip typesemiconductor back surface is from 0.9 MPa to 15 MPa. Therefore, byattaching the dicing tape-integrated film for semiconductor back surfaceonto a workpiece (semiconductor wafer) at dicing a wafer (semiconductorwafer), the workpiece can be effectively diced while being held. Also,after the workpiece is diced to form a chip-shaped workpiece(semiconductor element), the chip-shaped workpiece can be easily peeledfrom the pressure-sensitive adhesive layer of the dicing tape with anexcellent picking-up property together with the film for flip chip typesemiconductor back surface, and the back surface-protected chip-shapedworkpiece can be easily obtained. Moreover, a marking property, anappearance property and the like of the back surface of the chip-shapedworkpiece can be effectively enhanced.

In particular, as described previously, in the dicing tape-integratedfilm for semiconductor back surface of the invention, the dicing tapeand the film for flip chip type semiconductor back surface are formed inan integrated form, and therefore, the dicing tape-integrated film forsemiconductor back surface of the invention can also be provided for adicing step of dicing a semiconductor wafer to prepare a semiconductorelement or a subsequent picking-up step. As a result, a step ofattaching only a film for semiconductor back surface (attaching step ofa film for semiconductor back surface) is not required. Furthermore, inthe subsequent dicing step or picking-up step, the film forsemiconductor back surface is attached to the back surface of thesemiconductor wafer or the back surface of the semiconductor elementformed by dicing, and therefore, the semiconductor wafer or thesemiconductor element can be effectively protected, and the damage ofthe semiconductor element in the dicing step or subsequent steps (forexample, the picking-up step) can be suppressed or prevented.

In an embodiment, the film for flip chip type semiconductor back surfacecontains a coloring agent added thereto. In an embodiment, the dicingtape-integrated film for semiconductor back surface of the invention canbe suitably used at the time of flip chip bonding. Also, since the filmfor flip chip type semiconductor back surface attaches to the backsurface of the semiconductor element with excellent close adhesion, ithas an excellent appearance property. Furthermore, an excellent markingproperty can be imparted to the back surface of the semiconductorelement.

The present invention also provides a process for producing asemiconductor device using the above-mentioned dicing tape-integratedfilm for semiconductor back surface, the process comprising:

attaching a workpiece onto the film for flip chip type semiconductorback surface of the dicing tape-integrated film for semiconductor backsurface,

dicing the workpiece to form a chip-shaped workpiece,

peeling the chip-shaped workpiece from the pressure-sensitive adhesivelayer of the dicing tape together with the film for flip chip type backsurface, and

flip chip connecting the chip-shaped workpiece onto an adherend.

The present invention further provides a flip chip-mounted semiconductordevice, which is manufactured by the above-mentioned process.

According to the dicing tape-integrated film for semiconductor backsurface of the invention, not only the dicing tape and the film for flipchip type semiconductor back surface are formed in an integrated form,but the storage elastic modulus (at 60° C.) of the film for flip chiptype semiconductor back surface is from 0.9 MPa to 15 MPa. Therefore,the dicing tape-integrated film for semiconductor back surface of theinvention can be utilized from a dicing step of a semiconductor wafer toa flip chip bonding step of a semiconductor element. Specifically, thedicing tape-integrated film for semiconductor back surface of theinvention can exhibit an excellent holding force in the dicing step of asemiconductor wafer, and the semiconductor element by dicing can bepeeled from the pressure-sensitive adhesive layer of the dicing tapewith an excellent picking-up property together with the film for flipchip type semiconductor back surface in a picking-up step after thedicing step. Furthermore, a marking property and an appearance propertycan be exhibited during and after the flip chip bonding step of asemiconductor element. Also, in the flip chip bonding step and the like,since the back surface of the semiconductor element is protected withthe film for flip chip type semiconductor back surface, breakage,chipping, warp and the like of the semiconductor element can beeffectively suppressed or prevented. Furthermore, even when thesemiconductor element whose back surface is protected with the film forflip chip type semiconductor back surface is placed on a support afterthe picking-up step and up to the flip chip bonding step, thesemiconductor element is not attached to the support. As a matter ofcourse, the dicing tape-integrated film for semiconductor back surfaceof the invention can effectively exhibit its functions in steps otherthan the steps of from the dicing step to the flip chip bonding step ofa semiconductor element.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional schematic view showing one embodiment of adicing tape-integrated film for semiconductor back surface of theinvention.

FIGS. 2A to 2D are cross-sectional schematic views showing oneembodiment of a process for producing a semiconductor device using adicing tape-integrated film for semiconductor back surface of theinvention.

DESCRIPTION OF REFERENCE NUMERALS AND SIGNS

-   1: Dicing tape-integrated film for semiconductor back surface-   2: Film for flip chip type semiconductor back surface-   3: Dicing tape-   31: Base material-   32: Pressure-sensitive adhesive layer-   4: Semiconductor wafer (workpiece)-   5: Semiconductor element (semiconductor chip)-   51: Bump formed at circuit face of semiconductor chip 5-   6: Adherend-   61: Conductive material for conjunction adhered to connecting pad of    adherend 6

DETAILED DESCRIPTION OF THE INVENTION Dicing Tape-Integrated Film forSemiconductor Back Surface

An embodiment of the invention is described with reference to FIG. 1,but the invention is not restricted to this embodiment, FIG. 1 is asectional schematic view showing an embodiment of a dicingtape-integrated film for semiconductor back surface of the invention. InFIG. 1, 1 is a dicing tape-integrated film for semiconductor backsurface (hereinafter sometimes also referred to as “dicingtape-integrated semiconductor back surface protective film”, “film forsemiconductor back surface with dicing tape”, or “semiconductor backsurface protective film with dicing tape”); 2 is a film for flip chiptype semiconductor back surface (hereinafter sometimes also referred toas “film for semiconductor back surface” or “semiconductor back surfaceprotective film”); 3 is a dicing tape; 31 is a base material; and 32 isa pressure-sensitive adhesive layer.

Incidentally, in the figures in the present specification, parts thatare unnecessary for the description are not given, and there are partsshown by magnifying, minifying, etc. in order to make the descriptioneasy.

As shown in FIG. 1, the dicing tape-integrated film for semiconductorback surface 1 has a configuration including the dicing tape 3 havingthe pressure-sensitive adhesive layer 32 formed on the base material 31and the film for semiconductor back surface 2 provided on thepressure-sensitive adhesive layer 32. The film for semiconductor backsurface 2 has a storage elastic modulus (at 60° C.) of from 0.9 MPa to15 MPa. The surface of the film for semiconductor back surface 2(surface to be attached to the back surface of the semiconductor wafer)may be protected with a separator or the like during the period until itis attached to the back surface of the semiconductor wafer.

Also, the dicing tape-integrated film for semiconductor back surface 1may have a configuration in which the film for semiconductor backsurface 2 is formed on the pressure-sensitive adhesive layer 32 of thedicing tape 3 over the whole surface or may have a configuration inwhich the film for semiconductor back surface 2 is partially formed. Forexample, as shown in FIG. 1, the dicing tape-integrated film forsemiconductor back surface 1 may have a configuration in which the filmfor semiconductor back surface 2 is formed only on a portion of thepressure-sensitive adhesive layer 32 of the dicing tape 3, to which thesemiconductor wafer is to be attached.

Film for Flip Chip Type Semiconductor Back Surface

The film for semiconductor back surface 2 has a film shape. As describedpreviously, since the film for semiconductor back surface 2 has astorage elastic modulus (at 60° C.) of from 0.9 MPa to 15 MPa, in acut-processing step (dicing step) of cutting a semiconductor waferattached onto the film for semiconductor back surface 2 into a chipshape, the film for semiconductor back surface 2 has a function ofsupporting the semiconductor wafer with close adhesion thereto and isable to exhibit adhesiveness such that cut pieces are not scattered.Also, in a picking-up step after the dicing step, the dicedsemiconductor element can be easily peeled from the dicing tape 3together with the film for semiconductor back surface 2. Furthermore,after the picking-up step (after the diced semiconductor element ispeeled from the dicing tape 3 together with the film for semiconductorback surface 2), the film for semiconductor back surface 2 can havefunctions of protecting the back surface of the semiconductor element(semiconductor chip) and also exhibiting an excellent marking propertyand an excellent appearance property.

As above, since the film for semiconductor back surface 2 has anexcellent marking property, marking can be performed to impart variouskinds of information such as literal information and graphicalinformation to the face on the non-circuit side of a semiconductorelement or a semiconductor device using the semiconductor element byutilizing a printing method or a laser marking method through the filmfor semiconductor back surface 2. In particular, when the film forsemiconductor back surface 2 is colored, by controlling the color ofcoloring, it becomes possible to observe the information (for example,literal information and graphical information) imparted by marking withexcellent visibility. Also, when the film for semiconductor back surface2 is colored, the dicing tape 3 and the film for semiconductor backsurface 2 can be easily distinguished from each other, and workabilityand the like can be enhanced.

In particular, since the film for semiconductor back surface 2 hasexcellent close adhesion to the semiconductor wafer or the semiconductorchip, lifting or the like is not observed. Also, since the film forsemiconductor back surface 2 can exhibit an excellent appearanceproperty, a semiconductor device having an excellent value-addedappearance property can be obtained. For example, as a semiconductordevice, it is possible to classify products thereof by using differentcolors.

It is important that the film for semiconductor back surface 2 hasadhesiveness (close adhesion) such that cut pieces are not scattered atcut-processing of the semiconductor wafer.

As above, the film for semiconductor back surface 2 is used not fordie-bonding a semiconductor chip to an adherend such as a substrate butfor protecting the back surface (non-circuit face) of a semiconductorchip to be flip chip mounted (or having been flip chip mounted) and hasoptimal function and constitution therefor. In this regard, a diebonding film is an adhesive layer which is used for an application ofstrongly adhering the semiconductor chip onto the adherend such as asubstrate. Also, in the semiconductor device using a die bonding film,since it is finally encapsulated with an encapsulating resin, the diebonding film is different in function and constitution from the film forsemiconductor back surface 2 of the invention aiming to protect the backsurface of each of the semiconductor wafer and the semiconductor chip.Accordingly, it is not preferable that the film for semiconductor backsurface 2 of the invention is used as a die bonding film.

As described previously, in the invention, it is important that thestorage elastic modulus (at 60° C.) of the film for semiconductor backsurface 2 is from 0.9 MPa to 15 MPa. Although an upper limit of thestorage elastic modulus (at 60° C.) of the film for semiconductor backsurface 2 may be not more than 15 MPa, it is preferably not more than 12MPa, and more preferably not more than 10 MPa. Also, the upper limit ofthe storage elastic modulus (at 60° C.) of the film for semiconductorback surface 2 may be not more than 8 MPa, and it is especiallypreferably not more than 5 MPa. Above all, the upper limit of thestorage elastic modulus (at 60° C.) of the film for semiconductor backsurface 2 is suitably not more than 3 MPa. On the other hand, although alower limit of the storage elastic modulus (at 60° C.) of the film forsemiconductor back surface 2 may be 0.9 MPa or more, it is preferably 1MPa or more, and especially preferably 1.2 MPa or more. Accordingly, thestorage elastic modulus (at 60° C.) of the film for semiconductor backsurface 2 may be, for example, from 0.9 MPa to 12 MPa and may also befrom 0.9 MPa to 10 MPa. When the storage elastic modulus (at 60° C.) ofthe film for semiconductor back surface 2 exceeds 15 MPa, the closeadhesion to the wafer is lowered, and the holding force of thesemiconductor wafer in the dicing step is lowered. On the other hand,when the storage elastic modulus (at 60° C.) of the film forsemiconductor back surface 2 is less than 0.9 MPa, the elastic modulusis too low so that in the picking-up step, a peeling property at aninterface between the film for semiconductor back surface 2 and thepressure-sensitive adhesive layer 32 of the dicing tape 3 is lowered andthat the picking-up property is lowered.

The storage elastic modulus (tensile storage elastic modulus E′) at 60°C. of the film for semiconductor back surface 2 is determined bypreparing the film for semiconductor back surface 2 without beinglaminated on the dicing tape and measuring a storage elastic modulus ina tensile mode under conditions of a sample width of 10 mm, a samplelength of 22.5 mm, a sample thickness of 0.2 mm, a frequency of 1 Hz anda temperature elevating rate of 10° C./min under a nitrogen atmosphereat a prescribed temperature (60° C.) using a dynamic viscoelasticitymeasuring apparatus “Solid Analyzer RS A2”, manufactured by RheometricsCo., Ltd. and is regarded as a value of obtained tensile storage elasticmodulus E′.

In the invention, the film for semiconductor back surface 2 ispreferably constituted of a resin composition containing a thermoplasticresin and a thermosetting resin. The film for semiconductor back surface2 may be constituted of a thermoplastic resin composition which is freefrom a thermosetting resin or may be constituted of a thermosettingresin composition which is free from a thermoplastic resin.

Examples of the thermoplastic resin include natural rubber, butylrubber, isoprene rubber, chloroprene rubber, an ethylene-vinyl acetatecopolymer, an ethylene-acrylic acid copolymer, an ethylene-acrylic acidester copolymer, a polybutadiene resin, a polycarbonate resin, athermoplastic polyimide resin, a polyamide resin such as 6-nylon and6,6-nylon, a phenoxy resin, an acrylic resin, a saturated polyesterresin such as PET (polyethylene telephtalate) and PBT (polybutylenetelephtalate), a polyamide-imide resin and a fluorocarbon resin. Thethermoplastic resin may be used singly or in combinations of two or morekinds thereof. Among these thermoplastic resins, an acrylic resincontaining a small amount of ionic impurities, having high heatresistance and capable of securing reliability of a semiconductorelement is especially preferable.

The acrylic resins are not particularly restricted, and examples thereofinclude polymers containing one kind or two or more kinds of alkylesters of acrylic acid or methacrylic acid in which the alkyl group is astraight chain or branched alkyl group having 30 or less carbon atoms,especially 4 to 18 carbon atoms as component(s). Namely, “acrylic resin”as used herein has a broad meaning of including methacrylic resin.Examples of the alkyl group include a methyl group, an ethyl group, apropyl group, an isopropyl group, an n-butyl group, a t-butyl group, anisobutyl group, a pentyl group, an isopentyl group, a hexyl group, aheptyl group, a 2-ethylhexyl group, an octyl group, an isooctyl group, anonyl group, an isononyl group, a decyl group, an isodecyl group, anundecyl group, a dodecyl group (lauryl group), a tridecyl group, atetradecyl group, a stearyl group, and an octadecyl group.

Moreover, other monomers for forming the acrylic resins (monomers otherthan the alkyl esters of acrylic acid or methacrylic acid in which thealkyl group is one having 30 or less carbon atoms) are not particularlyrestricted, and examples thereof include carboxyl group-containingmonomers such as acrylic acid, methacrylic acid, carboxylethyl acrylate,carboxylpentyl acrylate, itaconic acid, maleic acid, fumaric acid, andcrotonic acid; acid anhydride monomers such as maleic anhydride anditaconic anhydride; hydroxyl group-containing monomers such as2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate,4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate,8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate,12-hydroxylauryl (meth)acrylate, and(4-hydroxymethylcyclohexyl)-methylacrylate; sulfonic acid-containingmonomers such as styrenesulfonic acid, allylsulfonic acid,2-(meth)acrylamido-2-methylpropanesulfonic acid,(meth)acrylamidopropanesulfonic acid, sulfopropyl (meth)acrylate, and(meth)acryloyloxynaphthalenesulfonic acid; and phosphoric acidgroup-containing monomers such as 2-hydroxyethylaoryloyl phosphate.

Examples of the thermosetting resin include, in addition to an epoxyresin and a phenol resin, an amino resin, an unsaturated polyesterresin, a polyurethane resin, a silicone resin and a thermosettingpolyimide resin. The thermosetting resin may be used singly or incombinations of two or more kinds thereof. As the thermosetting resin,an epoxy resin containing a small amount of ionic impurities whichcorrode a semiconductor element is suitable. Also, the phenol resin canbe suitably used as a curing agent of the epoxy resin.

The epoxy resin is not particularly restricted and, for example, adifunctional epoxy resin or a polyfunctional epoxy resin such as abisphenol A type epoxy resin, a bisphenol F type epoxy resin, abisphenol S type epoxy resin, a brominated bisphenol A type epoxy resin,a hydrogenated bisphenol A type epoxy resin, a bisphenol AF type epoxyresin, a biphenyl type epoxy resin, a naphthalene type epoxy resin, afluorene type epoxy resin, a phenol novolak type epoxy resin, ano-cresol novolak type epoxy resin, a trishydroxyphenylmethane type epoxyresin and a tetraphenylolethane type epoxy resin, or an epoxy resin suchas a hydantoin type epoxy resin, a trisglycidylisocyanurate type epoxyresin or a glycidylamine type epoxy resin may be used.

As the epoxy resin, among those exemplified above, bisphenol A typeepoxy resin, a novolak type epoxy resin, a biphenyl type epoxy resin, atrishydroxyphenylmethane type epoxy resin, and a tetraphenylolethanetype epoxy resin are preferable. This is because these epoxy resins havehigh reactivity with a phenol resin as a curing agent and are superiorin heat resistance and the like.

Furthermore, the above-mentioned phenol resin acts as a curing agent ofthe epoxy resin, and examples thereof include novolak type phenol resinssuch as phenol novolak resins, phenol aralkyl resins, cresol novolakresins, tert-butylphenol novolak resins, and nonylphenol novolak resins;resol type phenol resins; and polyoxystyrenes such as poly-p-oxystyrene.The phenol resin may be employed singly or in a combination of two ormore kinds. Among these phenol resins, phenol novolak resins and phenolaralkyl resins are particularly preferable. This is because connectionreliability of the semiconductor device can be improved.

The mixing ratio of the epoxy resin to the phenol resin is preferablymade, for example, such that the hydroxyl group in the phenol resinbecomes 0.5 to 2.0 equivalents per equivalent of the epoxy group in theepoxy resin component. It is more preferably 0.8 to 1.2 equivalents.That is when the mixing ratio becomes outside the range, a curingreaction does not proceed sufficiently, and the characteristics of theepoxy resin cured product tends to deteriorate.

A thermal curing-accelerating catalyst for the epoxy resins and thephenol resins is not particularly restricted and can be suitablyselected from known thermal curing-accelerating catalysts and used. Thethermal curing-accelerating catalyst may be employed singly or in acombination of two or more kinds. As the thermal curing-acceleratingcatalyst, for example, an amine-based curing-accelerating catalyst, aphosphorus-based curing-accelerating catalyst, an imidazole-basedcuring-accelerating catalyst, a boron-based curing-acceleratingcatalyst, or a phosphorus-boron-based curing-accelerating catalyst canbe used.

In the invention, it is especially preferable that the film forsemiconductor back surface 2 is formed of a resin composition (resincomposition for DBF) containing an epoxy resin, a phenol resin and anacrylic resin. Since these resins are small in ionic impurities and highin heat resistance, reliability of a semiconductor element can besecured. In this case, although a blending ratio of these resins is notparticularly limited, for example, a mixing amount of the epoxy resinand the phenol resin can be selected within the range of from 10 partsby weight to 300 parts by weight (preferably from 15 parts by weight to280 parts by weight, and more preferably from 20 parts by weight to 250parts by weight) based on 100 parts by weight of the acrylic resincomponent.

It is important that the film for semiconductor back surface 2 hasadhesiveness (close adhesion) to the back surface (non-circuit face) ofthe semiconductor wafer. The film for semiconductor back surface havingsuch close adhesion or the like can be for example, formed of a resincomposition containing an epoxy resin. For the purpose of crosslinkingthe film for semiconductor back surface 2, a polyfunctional compoundcapable of reacting with a molecular chain terminal functional group orthe like of a polymer can be added as a crosslinking agent thereto.According to this, it is possible to contrive to enhance an adhesivecharacteristic (close adhesion characteristic) at high temperatures andto improve heat resistance.

The crosslinking agent is not particularly restricted and knowncrosslinking agents can be used. Specifically, as the crosslinkingagent, not only isocyanate-based crosslinking agents, epoxy-basedcrosslinking agents, melamine-based crosslinking agents, andperoxide-based crosslinking agents but also urea-based crosslinkingagents, metal alkoxide-based crosslinking agents, metal chelate-basedcrosslinking agents, metal salt-based crosslinking agents,carbodiimide-based crosslinking agents, oxazoline-based crosslinkingagents, aziridine-based crosslinking agents, amine-based crosslinkingagents, and the like may be mentioned. As the crosslinking agent, anisocyanate-based crosslinking agent or an epoxy-based crosslinking agentis suitable. The crosslinking agent may be employed singly or in acombination of two or more kinds.

Examples of the isocyanate-based crosslinking agents include loweraliphatic polyisocyanates such as 1,2-ethylene diisocyanate,1,4-butylene diisocyanate, and 1,6-hexamethylene diisocyanate; alicyclicpolyisocyanates such as cyclopentylene diisocyanate, cyclohexylenediisocyanate, isophorone diisocyanate, hydrogenated tolylenediisocyanate, and hydrogenated xylylene diisocyanate; and aromaticpolyisocyanates such as 2,4-tolylene diisocyanate, 2,6-tolylenediisocyanate, 4,4′-diphenylmethane diisocyanate, and xylylenediisocyanate. In addition, a trimethylolpropane/tolylene diisocyanatetrimer adduct [trade name “COLONATE L” manufactured by NipponPolyurethane Industry Co., Ltd.], a trimethylolpropane/hexamethylenediisocyanate trimer adduct [trade name “COLONATE HL” manufactured byNippon Polyurethane Industry Co., Ltd.], and the like are also used.Moreover, examples of the epoxy-based crosslinking agents includeN,N,N′,N′-tetraglycidyl-m-xylenediamine, diglycidylaniline,1,3-bis(N,N-glycidylaminomethyl)cyclohexane, 1,6-hexanediol diglycidylether, neopentyl glycol diglycidyl ether, ethylene glycol diglycidylether, propylene glycol diglycidyl ether, polyethylene glycol diglycidylether, polypropylene glycol diglycidyl ether, sorbitol polyglycidylether, glycerol polyglycidyl ether, pentaerythritol polyglycidyl ether,polyglycerol polyglycidyl ether, sorbitan polyglycidyl ether,trimethylolpropnane polyglycidyl ether, adipic acid diglycidyl ester,o-phthalic acid diglycidyl ester, triglycidyl-tris(2-hydroxyethyl)isocyanurate, resorcin diglycidyl ether, and bisphenol-S-diglycidylether, and also epoxy-based resins having two or more epoxy groups inthe molecule.

The amount of the crosslinking agent is not particularly restricted andcan be appropriately selected depending on the degree of thecrosslinking. Specifically, it is preferable that the amount of thecrosslinking agent is, for example, 0.05 to 7 parts by weight based on100 parts by weight of the polymer components (particularly, a polymerhaving a functional group at the molecular chain end). When the amountof the crosslinking agent is more than 7 parts by weight based on 100parts by weight of the polymer components, the close adhesiveness islowered and thus unfavorable, whereas when it is less than 0.05 parts byweight, the cohesive force is not sufficient and thus unfavorable.

In the invention, instead of the use of the crosslinking agent ortogether with the use of the crosslinking agent, it is also possible toperform the crosslinking treatment by irradiation with an electron beamor ultraviolet light.

In the invention, it is preferable that the film for semiconductor backsurface 2 is colored. As above, in the case where the film forsemiconductor back surface 2 is colored (the case where the film forsemiconductor back surface 2 is neither colorless nor transparent), thecolor shown by coloring is not particularly limited but, for example, ispreferably dark color such as black, blue or red color, and black coloris especially preferable.

In the invention, dark color basically means a dark color having L*,defined in L*a*b* color space, of 60 or smaller (from 0 to 60),preferably 50 or smaller (from 0 to 50), and more preferably 40 orsmaller (from 0 to 40).

Moreover, black color basically means a black-based color having L*,defined in L*a*b* color space, of 35 or smaller (from 0 to 35),preferably 30 or smaller (from 0 to 30), and more preferably 25 orsmaller (from 0 to 25). In this regard, in the black color, each of a*and b*, defined in the L*a*b* color space, can be suitably selectedaccording to the value of L*. For example, both of a* and b* are withinthe range of preferably from −10 to 10, more preferably from −5 to 5,and especially preferably −3 to 3 (particularly 0 or about 0).

In the invention, L*, a* and b* defined in the L*a*b* color space can bedetermined by a measurement with a color difference meter (trade name“CR-200” manufactured by Minolta Ltd; color difference meter). TheL*a*b* color space is a color space recommended by the CommissionInternationale de l'Eclairage (CIE) in 1976, and means a color spacecalled CIE1976(L*a*b*) color space. Also, the L*a*b* color space isdefined in Japanese Industrial Standards in JIS 28729.

At coloring of the film for semiconductor back surface 2, according toan objective color, a colorant (coloring agent) can be used. As such acolorant, various dark-colored colorants such as black-coloredcolorants, blue-colored colorants, and red-colored colorants can besuitably used and black-colored colorants are especially suitable. Thecolorant may be any of pigments and dyes. The colorant may be employedsingly or in combination of two or more kinds. In this regard, as thedyes, it is possible to use any forms of dyes such as acid dyes,reactive dyes, direct dyes, disperse dyes, and cationic dyes. Moreover,also with regard to the pigments, the form thereof is not particularlyrestricted and can be suitably selected and used among known pigments.

The black-colored colorant is not particularly restricted and can be,for example, suitably selected from inorganic black-colored pigments andblack-colored dyes. Moreover, the black-colored colorant may be acolorant mixture in which a cyan-colored colorant (blue-green colorant),a magenta-colored colorant (red-purple colorant), and a yellow-colorantcolorant (yellow colorant) are mixed. The black-colored colorant may beemployed singly or in a combination of two or more kinds. Of course, theblack-colored colorant may be used in combination with a colorant of acolor other than black.

Specific examples of the black-colored colorant include carbon black(such as furnace black, channel black, acetylene black, thermal black,or lamp black), graphite, copper oxide, manganese dioxide, azo-typepigment (e.g., azomethine azo black), aniline black, perylene black,titanium black, cyanine black, active charcoal, ferrite (such asnon-magnetic ferrite or magnetic ferrite), magnetite, chromium oxide,iron oxide, molybdenum disulfide, a chromium complex, a composite oxidetype black pigment, and an anthraquinone type organic black pigment.

As the colorant other than black-colored colorant, for example, acyan-colored colorant, a magenta-colored colorant, and a yellow-colorantcolorant may be mentioned. Examples of the cyan-colored colorantsinclude cyan-colored dyes such as C.I. Solvent Blue 25, 36, 60, 70, 93,95; C.I. Acid Blue 6 and 45; cyan-colored pigments such as C.I. PigmentBlue 1, 2, 3, 15, 15:1, 15:2, 15:3, 15:4, 15:5, 15:6, 16, 17, 17:1, 18,22, 25, 56, 60, 63, 65, 66; C.I. Vat Blue 4, 60; and C.I. Pigment Green7.

Moreover, among the magenta colorants, examples of magenta-colored dyeinclude C.I. Solvent Red 1, 3, 8, 23, 24, 25, 27, 30, 49, 52, 58, 63,81, 82, 83, 84, 100, 109, 111, 121, 122; C.I. Disperse Red 9; C.I.Solvent Violet 8, 13, 14, 21, 27; C.I. Disperse Violet 1; C.I. Basic Red1, 2, 9, 12, 13, 14, 15, 17, 18, 22, 23, 24, 27, 29, 32, 34, 35, 36, 37,38, 39, 40; C.I. Basic Violet 1, 3, 7, 10, 14, 15, 21, 25, 26, 27 and28.

Among the magenta-colored colorants, examples of magenta-colored pigmentinclude C.I. Pigment Red 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,15, 16, 17, 18, 19, 21, 22, 23, 30, 31, 32, 37, 38, 39, 40, 41, 42,48:1, 48:2, 48:3, 48:4, 49, 49:1, 50, 51, 52, 52:2, 53:1, 54, 55, 56,57:1, 58, 60, 60:1, 63, 63:1, 63:2, 64, 64:1, 67, 68, 81, 83, 87, 88,89, 90, 92, 101, 104, 105, 106, 108, 112, 114, 122, 123, 139, 144, 146,147, 149, 150, 151, 163, 166, 168, 170, 171, 172, 175, 176, 177, 178,179, 184, 185, 187, 190, 193, 202, 206, 207, 209, 219, 222, 224, 238,245; C.I. Pigment Violet 3, 9, 19, 23, 31, 32, 33, 36, 38, 43, 50; C.I.Vat Red 1, 2, 10, 13, 15, 23, 29 and 35.

Moreover, examples of the yellow-colored colorants includeyellow-colored dyes such as C.I. Solvent Yellow 19, 44, 77, 79, 81, 82,93, 98, 103, 104, 112, and 162; yellow-colored pigments such as C.I.Pigment Orange 31, 43; C.I. Pigment Yellow 1, 2, 3, 4, 5, 6, 7, 10, 11,12, 13, 14, 15, 16, 17, 23, 24, 34, 35, 37, 42, 53, 55, 65, 73, 74, 75,81, 83, 93, 94, 95, 97, 98, 100, 101, 104, 108, 109, 110, 113, 114, 116,117, 120, 128, 129, 133, 138, 139, 147, 150, 151, 153, 154, 155, 156,167, 172, 173, 180, 185, 195; C.I. Vat Yellow 1, 3, and 20.

Various colorants such as cyan-colored colorants, magenta-coloredcolorants, and yellow-colorant colorants may be employed singly or in acombination of two or more kinds, respectively. In this regard, in thecase that two or more kinds of various colorants such as cyan-coloredcolorants, magenta-colored colorants, and yellow-colorant colorants areused, the mixing ratio (or blending ratio) of these colorants is notparticularly restricted and can be suitably selected according to thekind of each colorant, an objective color, and the like.

Incidentally, in the case that the black-colored colorant is a colorantmixture formed by mixing a cyan-colored colorant, a magenta-coloredcolorant and a yellow-colored colorant, these colorants may be usedsingly or in a combination of two or more kinds. The mixing ratio (orblending ratio) of the cyan-colored colorant, the magenta-coloredcolorant and the yellow-colored colorant in the mixed ink composition isnot particularly restricted as long as a black-based color (e.g., ablack-based color having L*, a*, and b*, defined in L*a*b* color space,within the above ranges) can be exhibited, and may be suitably selectedaccording to the type of each colorant and the like. The contents of thecyan-colored colorant, the magenta-colored colorant and theyellow-colored colorant in the mixed ink composition can be suitablyselected, for example, within a range, with respect to the total amountof the colorants, of cyan-colored colorant/magenta-coloredcolorant/yellow-colored colorant=10% by weight to 50% by weight/10% byweight to 50% by weight/10% by weight to 50% by weight (preferably 20%by weight to 40% by weight/20% by weight to 40% by weight/20% by weightto 40% by weight).

As the black-colored colorant, black-colored dyes such as C.I. SolventBlack 3, 7, 22, 27, 29, 34, 43, 70, C.I. Direct Black 17, 19, 22, 32,38, 51, 71, C.I. Acid Black 1, 2, 24, 26, 31, 48, 52, 107, 109, 110,119, 154, and C.I. Disperse Black 1, 3, 10, 24; black-colored pigmentssuch as C.I. Pigment Black 1, 7; and the like can be utilized.

As such black-colored colorants, for example, trade name “Oil Black BY”,trade name “Oil Black BS”, trade name “Oil Black HBB”, trade name “OilBlack 803”, trade name “Oil Black 860”, trade name “Oil Black 5970”,trade name “Oil Black 5906”, trade name “Oil Black 5905” (manufacturedby Orient Chemical Industries Co., Ltd.), and the like are commerciallyavailable.

In the film for semiconductor back surface 2, if desired, otheradditives may be properly blended. Examples of other additives includean extender, an antiaging agent, an antioxidant and a surfactant inaddition to a filler, a flame retardant, a silane coupling agent and anion-trapping agent.

The filler may be any of an inorganic filler and an organic filler butan inorganic filler is suitable. By blending a filler such as aninorganic filler, imparting of electric conductivity to the film forsemiconductor back surface 2, improvement of the thermal conductivity ofthe film for semiconductor back surface 2, control of elastic modulus ofthe film for semiconductor back surface 2, and the like can be achieved.In this regard, the film for semiconductor back surface 2 may beelectrically conductive or non-conductive. Examples of the inorganicfiller include various inorganic powders composed of silica, clay,gypsum, calcium carbonate, barium sulfate, alumina oxide, berylliumoxide, ceramics such as silicone carbide and silicone nitride, metals oralloys such as aluminum, copper, silver, gold, nickel, chromium, lead,tin, zinc, palladium, and solder, carbon, and the like. The filler maybe employed singly or in a combination of two or more kinds.Particularly, the filler is suitably silica and especially suitablyfused silica. The average particle diameter of the inorganic filler ispreferably within the range of 0.1 μn to 80 μm. The average particlediameter of the inorganic filler can be measured by a laserdiffraction-type particle size distribution measurement apparatus.

A blending amount of the filler (in particular, an inorganic filler) ispreferably not more than 80 parts by weight (for example, from 0 part byweight to 80 parts by weight), and especially preferably from 0 part byweight to 70 parts by weight, based on 100 parts by weight of the resincomponents.

Examples of the flame retardant include antimony trioxide, antimonypentoxide, and brominated epoxy resins. The flame retardant may beemployed singly or in a combination of two or more kinds. Examples ofthe silane coupling agent includeβ-(3,4-epoxycyclohexyl)ethyltrimethoxysilane,γ-glycidoxypropyltrimethoxysilane, andγ-glycidoxypropylmethyldiethoxysilane. The silane coupling agent may beemployed singly or in a combination of two or more kinds. Examples ofthe ion-trapping agent include hydrotalcites and bismuth hydroxide. Theion-trapping agent may be employed singly or in a combination of two ormore kinds.

The film for semiconductor back surface 2 can be, for example, formed byutilizing a customary method in which a thermosetting resin componentsuch as an epoxy resin, a thermoplastic resin component such as anacrylic resin and a coloring material (coloring agent) and optionally, asolvent and other additives and the like are mixed to prepare a resincomposition, which is then formed in a film-shaped layer. Specifically,for example, the film-shaped layer as the film for semiconductor backsurface 2 can be formed by a method of coating the resin composition onthe pressure-sensitive adhesive layer 32 of the dicing tape 3; a methodof coating the resin composition on an appropriate separator (forexample, a release paper) to form a resin layer, which is thentransferred (transcribed) onto the pressure-sensitive adhesive layer 32of the dicing tape 3; or the like.

In the case where the film for semiconductor back surface 2 is formed ofa resin composition containing a thermosetting resin component such asan epoxy resin, in the film for semiconductor back surface 2, thethermosetting resin is in an uncured or partially cured state at a stagebefore it is applied to a semiconductor wafer. In this case, after it isapplied to the semiconductor wafer (specifically, in general, at thetime when an encapsulating material is cured in the flip chip bondingstep), the thermosetting resin component in the film for semiconductorback surface 2 is completely or almost completely cured.

As above, since the film for semiconductor back surface 2 is in a statein which the thermosetting resin component is uncured or partially curedeven though the film contains a thermosetting resin component, a gelfraction of the film for semiconductor back surface 2 is notparticularly restricted but can be, for example, suitably selectedwithin the range of not more than 50% by weight (from 0% by weight to50% by weight), and it is preferably not more than 30% by weight (from0% by weight to 30% by weight), and especially preferably not more than10% by weight (from 0% by weight to 10% by weight).

The gel fraction of the film for semiconductor back surface 2 can bemeasured in the following measuring method. That is, about 0.1 g of asample is sampled from the film for semiconductor back surface 2 andprecisely weighed (weight of sample), and after the sample is wrapped ina mesh-type sheet, it is immersed in about 50 mL, of toluene at roomtemperature for 1 week. Thereafter, a solvent-insoluble matter (contentin the mesh-type sheet) is taken out of the toluene and dried at 130° C.for about 2 hours, the solvent-insoluble matter after drying is weighed(weight after immersion and drying), and a gel fraction (% by weight) isthen calculated according to the following expression (a).

Gel fraction (% by weight)=[(Weight after immersion and drying)/(Weightof sample)]×100  (a)

The gel fraction of the film for semiconductor back surface 2 can becontrolled by the kind and content of the resin components and the kindand content of the crosslinking agent and besides, heating temperature,heating time and the like.

The film for semiconductor back surface 2 is a film-shaped material, andwhen colored, its coloring form is not particularly limited. The filmfor semiconductor back surface 2 may be for example, a film-shapedmaterial formed of a resin composition containing a thermoplastic resincomponent and/or a thermosetting resin component, a coloring agent andthe like. The film for semiconductor back surface 2 may also be afilm-shaped material having a configuration in which a resin layerformed of a resin composition containing a thermoplastic resin componentand/or a thermosetting resin component and the like and a coloring agentlayer are laminated.

In the case where the film for semiconductor back surface 2 is alaminate of a resin layer and a coloring agent layer, it is preferablethat the film for semiconductor back surface 2 has a laminated form of(resin layer)/(coloring agent layer)/(resin layer). In this case, thetwo resin layers located on the both sides of the coloring agent layermay be a resin layer of the same composition or may be a resin layerhaving a different composition from each other.

In the invention, in the case where the film for semiconductor backsurface 2 is a film-shaped material formed of a resin compositioncontaining a thermosetting resin component such as an epoxy resin, closeadhesion to the semiconductor wafer can be effectively exhibited.

In view of the fact that cutting water is used in the dicing step of aworkpiece (semiconductor wafer), there may be the case where the filmfor semiconductor back surface 2 has a water content of an ordinarystate or more upon absorption of moisture. When flip chip bonding isperformed in such a high water content state as it is, there may be thecase where water vapor remains at an adhesive (closely adhesive)interface between the film for semiconductor back surface 2 and theworkpiece or a processed material thereof (for example, a chip-shapedworkpiece), thereby causing lifting. Accordingly, when the film for flipchip type semiconductor back surface is configured to include, as aninternal layer, a layer made of a core material with high moisturepermeability, the water vapor is diffused, whereby such a problem can beavoided. From such a viewpoint, the film for semiconductor back surface2 may have a multilayered structure in which a layer made of a resincomposition for forming the film for semiconductor back surface 2 isformed on one face or both faces of a core material. Examples of thecore material include films (for example, a polyimide film, a polyesterfilm, a polyethylene terephthalate film, a polyethylene naphthalate filmand a polycarbonate film), resin substrates reinforced with glass fibersor plastic-made nonwoven fibers, silicon substrates and glasssubstrates.

A thickness (total thickness in the case of a laminated film) of thefilm for semiconductor back surface 2 is not particularly limited, butit can be, for example, properly selected within the range of from about5 μm to 500 μm. Furthermore, the thickness of the film for semiconductorback surface 2 is preferably from about 5 μm to 150 μm, and morepreferably from about 5 μm to 100 μm. The film for semiconductor backsurface 2 may be in any form of a single layer or a laminate.

As described previously, the film for semiconductor back surface 2 has astorage elastic modulus (at 60° C.) of from 0.9 MPa to 15 MPa and hasfavorable close adhesion (adhesiveness) to the semiconductor wafer. Anadhesive force of the film for semiconductor back surface 2 to thesemiconductor wafer is preferably 1 N/10 mm-width or more (for example,from 1 N/10 mm-width to 10 N/10 mm-width), more preferably 2 N/10mm-width or more (for example, from 2 N/10 mm-width to 10 N/10mm-width), and especially preferably 4 N/10 mm-width or more (forexample, from 4 N/10 mm-width to 10 N/10 mm-width). When the adhesiveforce of the film for semiconductor back surface 2 to the semiconductorwafer is less than 1 N/10 mm-width, the dicing property is lowered.

The adhesive force of the film for semiconductor back surface 2 withrespect to a semiconductor wafer is, for example, a value measured inthe following manner. That is, a pressure-sensitive adhesive tape (atrade name: BT315, manufactured by Nitto Denko Corporation) is attachedto one face of the film for semiconductor back surface 2, therebyreinforcing the back surface. Thereafter, a semiconductor wafer having athickness of 0.6 mm is attached onto the surface of the backsurface-reinforced film for semiconductor back surface 2 having a lengthof 150 mm and a width of 10 mm by reciprocating a roller of 2 kg at 50°C. once by a thermal laminating method. Thereafter, the laminate isallowed to stand on a hot plate (50° C.) for 2 minutes and then allowedto stand at ordinary temperature (about 23° C.) for 20 minutes. Afterstanding, the back surface-reinforced film for semiconductor backsurface 2 is peeled at a temperature of 23° C. under conditions of apeel angle of 180° and a tensile rate of 300 mm/min by using a peeltester (a trade name: AUTOGRAPH AGS-J, manufactured by ShimadzuCorporation). The adhesive force is a value (N/10 mm-width) measured bypeeling at an interface between the film for semiconductor back surface2 and the semiconductor wafer at this time.

An elastic modulus (tensile storage elastic modulus) at 23° C. of thefilm for semiconductor back surface 2 of the invention is preferably 1GPa or more, more preferably 2 GPa or more, and especially preferably 3GPa or more. When the tensile storage elastic modulus of the film forsemiconductor back surface 2 is 1 GPa or more, at the time when asemiconductor element is peeled from the pressure-sensitive layer of thedicing tape together with the film for semiconductor back surface 2, andthe film for semiconductor back surface 2 is then placed on the support(for example, a carrier tape) to perform transportation or the like, theattachment of the film for semiconductor back surface 2 to the support(for example, a top tape or a bottom tape in the carrier tape) can beeffectively suppressed or prevented. In the case where the film forsemiconductor back surface 2 is formed of a resin composition containinga thermosetting resin, as described previously, since the thermosettingresin is usually in an uncured or partially cured state, the tensilestorage elastic modulus at 23° C. of the film for semiconductor backsurface 2 is usually a value in a state in which the thermosetting resinis uncured or partially cured.

Here, though the film for semiconductor back surface 2 may be a singlelayer or may be a laminated film obtained by laminating plural layers,in the case of a laminated film, the tensile storage elastic modulus maybe 1 GPa or more as a whole of the laminated film. Also, the foregoingtensile storage elastic modulus (at 23° C.) of the film forsemiconductor back surface 2 in an uncured state can be controlled bysuitably setting up the kind and content of the resin components(thermoplastic resin and/or thermosetting resin) or the kind and contentof a filler such as a silica filler.

The elastic modulus (tensile storage elastic modulus) at 23° C. of thefilm for semiconductor back surface 2 is determined by preparing thefilm for semiconductor back surface 2 without being laminated on thedicing tape and measuring an elastic modulus in a tensile mode underconditions of a sample width of 10 mm, a sample length of 22.5 mm, asample thickness of 0.2 mm, a frequency of 1 Hz and a temperatureelevating rate of 10° C./min under a nitrogen atmosphere at a prescribedtemperature (23° C.) using a dynamic viscoelasticity measuring apparatus“Solid Analyzer RS A2”, manufactured by Rheometrics Co., Ltd. and isregarded as a value of obtained tensile storage elastic modulus.

A light transmittance (visible light transmittance) of the film forsemiconductor back surface 2 in a visible light region (wavelength: from400 nm to 800 nm) is not particularly restricted but is, for example,preferably in the range of not more than 20% (from 0% to 20%), morepreferably in the range of not more than 10% (from 0% to 10%), andespecially preferably in the range of not more than 5% (from 0% to 5%).When the light transmittance of the film for semiconductor back surface2 in a visible light region is not more than 20%, the visible lighttransmits through the film for semiconductor back surface 2 and reachesa semiconductor chip, whereby adverse influences against thesemiconductor chip can be diminished.

The visible light transmittance (%) of the film for semiconductor backsurface 2 can be controlled by the kind and content of the resincomponents constituting the film for semiconductor back surface 2, thekind and content of a coloring agent (for example, a pigment and a dye),the kind and content of a filler and the like.

The visible light transmittance (%) can be, for example, calculated inthe following manner. That is, the film for semiconductor back surface 2having a thickness (average thickness) of 20 μm is prepared withoutbeing laminated on the dicing tape. Next, the film for semiconductorback surface 2 is irradiated with visible light using “ABSORPTIONSPECTRO PHOTOMETER” (a trade name of Shimadzu Corporation). The visiblelight has a wavelength of from 400 nm to 800 nm. The light intensity ofthe visible light which has transmitted through the film forsemiconductor back surface 2 by this irradiation can be calculatedaccording to the following expression.

Visible light transmittance (%)=[(Light intensity of visible light aftertransmitting through the film for semiconductor back surface 2)/(Initiallight intensity of visible light)]×100

The foregoing calculation method of the light transmittance (%) can alsobe applied to the calculation of a light transmittance (%) of a film forsemiconductor back surface whose thickness is not 20 μn. Specifically,in accordance with the Lambert-Beer law, an absorbance A₂₀ in the caseof the thickness of 20 μm can be calculated as follows.

A ₂₀ −α×L ₂₀ ×C  (1)

(In the formula, L₂₀ is a length of light path, α is an absorbanceindex, C is a concentration of sample.)

In addition, an absorbance A_(X) in the case of the thickness of X (μm)can be calculated as follows.

A _(X) =α×L _(X) ×C  (2)

Moreover, absorbance A₂₀ in the case of the thickness of 20 μm can becalculated as follows.

A ₂₀=−log₁₀ T ₂₀  (3)

(In the formula, T₂₀ is a light transmittance in the case of thethickness of 20 μm.)

From the formulae (1) to (3) above, absorbance A_(X) can be representedby the following formula.

A _(X) =A ₂₀×(L _(X) /L ₂₀)=−[log₁₀(T ₂₀)]×(L _(X) /L ₂₀)

Therefore, a light transmittance T_(X) (%) in the case of the thicknessof X μm can be calculated as follows:

T_(X)=10^(−Ax)

wherein A_(X)=−[log₁₀(T₂₀)]×(L_(X)/L₂₀).

Also, the fact that the thickness of the film for semiconductor backsurface in the foregoing calculation method of a light transmittance (%)is regulated to 20 μm does not particularly restrict the thickness ofthe film for semiconductor back surface 2 of the invention. The value of“20 μm” is a thickness employed for the sake of convenience at themeasurement.

Also, the film for semiconductor back surface 2 preferably has a lowmoisture absorbance. Specifically, the moisture absorbance is preferablynot more than 1% by weight, and more preferably not more than 0.8% byweight. By regulating the moisture absorbance to not more than 1% byweight, the laser marking property can be enhanced. Also, for example,the generation of voids can be suppressed or prevented in a reflow step.The moisture absorbance can be, for example, regulated by changing anaddition amount of an organic filler. The moisture absorbance is a valuecalculated from a weight change when the film is allowed to stand underan atmosphere at 85° C. and 85% RH for 168 hours (see the followingexpression). Also, in the case where the film for semiconductor backsurface 2 is formed of a resin composition containing a thermosettingresin, the moisture absorbance is a value calculated from a weightchange when the film is allowed to stand under an atmosphere at 85° C.and 85% RH for 168 hours after thermal curing.

Moisture absorbance (% by weight)=[{(Weight after allowing the coloredfilm for semiconductor back surface to stand)−(Weight before allowingthe colored film for semiconductor back surface to stand)}/(Weightbefore allowing the colored film for semiconductor back surface tostand)]×100

Furthermore, the film for semiconductor back surface 2 preferably has asmall ratio of a volatile matter. Specifically, the ratio of a weightdecrease (weight decrease ratio) after heating at a temperature of 250°C. for 1 hour is preferably not more than 1% by weight, and morepreferably not more than 0.8% by weight. By regulating the weightdecrease ratio to not more than 1% by weight, the laser marking propertycan be enhanced. Also, for example, the generation of cracks in apackage can be suppressed or prevented in the reflow step. The weightdecrease ratio can be, for example, regulated by adding an inorganicmaterial capable of reducing the generation of cracks at the time oflead-free solder reflow. The weight decrease ratio is a value calculatedfrom a weight change when the film is heated under a condition at 250°C. for 1 hour (see the following expression). Also, in the case wherethe film for semiconductor back surface 2 is formed of a resincomposition containing a thermosetting resin, the weight decrease ratiois a value calculated from a weight change when the film is allowed tostand under a condition at 250° C. for 1 hour after thermal curing.

Weight decrease ratio (% by weight)=[{(Weight before allowing thecolored film for semiconductor back surface to stand)−(Weight afterallowing the colored film for semiconductor back surface tostand)}/(Weight before allowing the colored film for semiconductor backsurface to stand)]×100

The film for semiconductor back surface 2 (in particular, the waferadhesion layer 22) is preferably protected by a separator (releaseliner) (not shown in Figures). The separator has a function as aprotective material for protecting the film for semiconductor backsurface 2 (in particular, the wafer adhesion layer 22) until it is putinto practical use. Also, the separator can be further used as asupporting base material at transfer of the film for semiconductor backsurface 2 to the pressure-sensitive adhesive layer 32 on the basematerial 31 of the dicing tape 3. The separator is peeled when aworkpiece is attached onto the film for semiconductor back surface 2 ofthe dicing tape-integrated film for semiconductor back surface 1. As theseparator, polyethylene or polypropylene, a plastic film (for example,polyethylene terephthalate) or paper whose surface is coated with areleasing agent such as a fluorine based releasing agent and a longchain alkyl acrylate based releasing agent can also be used. Theseparator can be formed by a conventionally known method. Also, athickness or the like of the separator is not particularly restricted.

Dicing Tape

The dicing tape 3 is constituted by a base material 31 and apressure-sensitive adhesive layer 32 formed on the base material 31.Thus, the dicing tape 3 sufficiently has a constitution that the basematerial 31 and the pressure-sensitive adhesive layer 32 are laminated.The base material 31 (supporting base material) can be used as asupporting material for the pressure-sensitive adhesive layer 32 and thelike. As the base material 31, for example, suitable thin materials,e.g., paper-based base materials such as paper; fiber-based basematerials such as fabrics, non-woven fabrics, felts, and nets;metal-based base materials such as metal foils and metal plates; plasticbase materials such as plastic films and sheets; rubber-based basematerials such as rubber sheets; foamed bodies such as foamed sheets;and laminates thereof [particularly, laminates of plastic basedmaterials with other base materials, laminates of plastic films (orsheets) each other, etc.] can be used. In the invention, as the basematerial, plastic base materials such as plastic films and sheets can besuitably employed. Examples of raw materials for such plastic materialsinclude olefinic resins such as polyethylene (PE), polypropylene (PP),and ethylene-propylene copolymers; copolymers using ethylene as amonomer component, such as ethylene-vinyl acetate copolymers (EVA),ionomer resins, ethylene-(meth)acrylic acid copolymers, andethylene-(meth)acrylic acid ester (random, alternating) copolymers;polyesters such as polyethylene terephthalate (PET), polyethylenenaphthalate (PEN), and polybutylene terephthalate (PBT); acrylic resins;polyvinyl chloride (PVC); polyurethanes; polycarbonates; polyphenylenesulfide (PPS); amide-based resins such as polyamides (Nylon) and wholearomatic polyamides (aramide); polyether ether ketones (PEEK);polyimides; polyetherimides; polyvinylidene chloride; ABS(acrylonitrile-butadiene-styrene copolymers); cellulose-based resins;silicone resins; and fluorinated resins. Moreover, as the material ofthe base material, a polymer such as a cross-linked body of each of theabove resins can also be used. These raw materials may be employedsingly or in a combination of two or more kinds.

In the case where a plastic base material 31 is used as the basematerial, deformation properties such as an elongation degree may becontrolled by a stretching treatment or the like.

The thickness of the base material 31 is not particularly restricted andcan be appropriately selected depending on strength, flexibility,intended purpose of use, and the like. For example, the thickness isgenerally 1000 μm or less (e.g., 1 to 1000 μm), preferably 1 to 500 μm,further preferably 3 to 300 μm, and especially about 5 to 250 μm but isnot limited thereto. In this regard, the base material 31 may have anyform of a single layer form and a laminated layer form.

A commonly used surface treatment, e.g., a chemical or physicaltreatment such as a chromate treatment, ozone exposure, flame exposure,exposure to high-voltage electric shock, or an ionized radiationtreatment, or a coating treatment with an undercoating agent can beapplied on the surface of the base material 31 in order to improve closeadhesiveness with the adjacent layer, holding properties, etc.

Incidentally, the base material 31 may contain various additives (acoloring agent, a filler, a plasticizer, an antiaging agent, anantioxidant, a surfactant, a flame retardant, etc.) within the rangewhere the advantages and the like of the invention are not impaired.

The pressure-sensitive adhesive layer 32 is formed of apressure-sensitive adhesive and has pressure-sensitive adhesiveness.Such a pressure-sensitive adhesive is not particularly restricted andcan be suitably selected among known pressure-sensitive adhesives.Specifically, as the pressure-sensitive adhesive, a pressure-sensitiveadhesive having the above-mentioned characteristics can be suitablyselected and used among known pressure-sensitive adhesives such asacrylic pressure-sensitive adhesives, rubber-based pressure-sensitiveadhesives, vinyl alkyl ether-based pressure-sensitive adhesives,silicone-based pressure-sensitive adhesives, polyester-basedpressure-sensitive adhesives, polyamide-based pressure-sensitiveadhesives, urethane-based pressure-sensitive adhesives, fluorine-basedpressure-sensitive adhesives, styrene-diene block copolymer-basedpressure-sensitive adhesives, and creep characteristic-improvingpressure-sensitive adhesives in which a heat-meltable resin having amelting point of about 200° C. or lower is mixed into thesepressure-sensitive adhesives (see, e.g., JP-A-56-61468, JP-A-61-174857,JP-A-63-17981, JP-A-56-13040, etc., each of which herein incorporated byreference). Moreover, as the pressure-sensitive adhesives,radiation-curable pressure-sensitive adhesives (or energy ray-curablepressure-sensitive adhesives) or heat-expandable pressure-sensitiveadhesives can be also used. The pressure-sensitive adhesive may beemployed singly or in a combination of two or more kinds.

In the invention, as the pressure-sensitive adhesive, acrylicpressure-sensitive adhesives and rubber-based pressure-sensitiveadhesives can be suitably used and particularly, acrylicpressure-sensitive adhesives are suitable. As the acrylicpressure-sensitive adhesives, there may be mentioned acrylicpressure-sensitive adhesives in which an acrylic polymer (homopolymer orcopolymer) using one or more alkyl (meth)acrylates ((meth)acrylic acidalkyl ester) as monomer components is used as the base polymer.

Examples of the alkyl (meth)acrylates in the above-mentioned acrylicpressure-sensitive adhesives include alkyl (meth)acrylates such asmethyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate,isopropyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate,s-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate,hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate,2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, nonyl(meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, isodecyl(meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, tridecyl(meth)acrylate, tetradecyl (meth)acrylate, pentadecyl (meth)acrylate,hexadecyl (meth)acrylate, heptadecyl (meth)acrylate, octadecyl(meth)acrylate, nonadecyl (meth)acrylate, and eicosyl (meth)acrylate. Asthe alkyl (meth)acrylates, alkyl (meth)acrylates having an alkyl grouphaving 4 to 18 carbon atoms are suitable. Incidentally, the alkyl groupof the alkyl (meth)acrylate may be linear or branched.

The above-mentioned acrylic polymer may contain units corresponding toother monomer components (copolymerizable monomer components)polymerizable with the above-mentioned alkyl (meth)acrylates for thepurpose of modifying cohesive force, heat resistance, crosslinkingability, and the like. Examples of such copolymerizable monomercomponents include carboxyl group-containing monomers such as(meth)acrylic acid (acrylic acid or methacrylic acid), carboxyethylacrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaricacid, and crotonic acid; acid anhydride group-containing monomers suchas maleic anhydride and itaconic anhydride; hydroxyl group-containingmonomers such as hydroxyethyl (meth)acrylate, hydroxypropyl(meth)acrylate, hydroxybutyl (meth)acrylate, hydroxyhexyl(meth)acrylate, hydroxyoctyl (meth)acrylate, hydroxydecyl(meth)acrylate, hydroxylauryl (meth)acrylate, and(4-hydroxymethylcyclohexyl)methyl methacrylate; sulfonic acidgroup-containing monomers such as styrenesulfonic acid, allylsulfonicacid, 2-(meth)acrylamide-2-methylpropanesulfonic acid,(meth)acrylamidepropanesulfonic acid, sulfopropyl (meth)acrylate, and(meth)acryloyloxynaphthalenesulfonic acid; phosphoric acidgroup-containing monomers such as 2-hydroxyethylacryloyl phosphate;(N-substituted)amide-based monomers such as (meth)acrylamide,N,N-dimethyl(meth)acrylamide, N-butyl(meth)acrylamide,N-methylol(meth)acrylamide, and N-methylolpropane(meth)acrylamide;aminoalkyl (meth)acrylate-based monomers such as aminoethyl(meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, andt-butylaminoethyl (meth)acrylate; alkoxyalkyl (meth)acrylate-basedmonomers such as methoxyethyl (meth)acrylate and ethoxyethyl(meth)acrylate; cyanoacrylate monomers such as acrylonitrile andmethacrylonitrile; epoxy group-containing acrylic monomers such asglycidyl (meth)acrylate; styrene-based monomers such as styrene and amethylstyrene; vinyl ester-based monomers such as vinyl acetate andvinyl propionate; olefin-based monomers such as isoprene, butadiene, andisobutylene; vinyl ether-based monomers such as vinyl ether;nitrogen-containing monomers such as N-vinylpyrrolidone,methylvinylpyrrolidone, vinylpyridine, vinylpiperidone, vinylpyrimidine,vinylpiperazine, vinylpyrazine, vinylpyrrole, vinylimidazole,vinyloxazole, vinylmorpholine, N-vinylcarboxylic acid amides, andN-vinylcaprolactam; maleimide-based monomers such asN-cyclohexylmaleimide, N-isopropylmaleimide, N-laurylmaleimide, andN-phenylmaleimide; itaconimide-based monomers such asN-methylitaconimide, N-ethylitaconimide, N-butylitaconimide,N-octylitaconimide, N-2-ethylhexylitaconimide, N-cyclohexylitaconimide,and N-laurylitaconimide; succinimide-based monomers such asN-(meth)acryloyloxymethylenesuccinimide,N-(meth)acryloyl-6-oxyhexamethylenesuccinimide, andN-(meth)acryloyl-8-oxyoctamethylenesuccinimide; glycol-based acrylicester monomers such as polyethylene glycol (meth)acrylate, polypropyleneglycol (meth)acrylate, methoxyethylene glycol (meth)acrylate, andmethoxypolypropylene glycol (meth)acrylate; acrylic acid ester-basedmonomers having a heterocycle, a halogen atom, a silicon atom, or thelike, such as tetrahydrofurfuryl (meth)acrylate, fluorine(meth)acrylate, and silicone (meth)acrylate; polyfunctional monomerssuch as hexanediol di(meth)acrylate, (poly)ethylene glycoldi(meth)acrylate, (poly)propylene glycol di(meth)acrylate, neopentylglycol di(meth)acrylate, pentaerythritol di(meth)acrylate,trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate,dipentaerythritol hexa(meth)acrylate, epoxy acrylate, polyesteracrylate, urethane acrylate, divinylbenzene, butyl di(meth)acrylate, andhexyl di(meth)acrylate; and the like. These copolymerizable monomercomponents may be employed singly or in a combination of two or morekinds.

In the case that a radiation-curable pressure-sensitive adhesive (or anenergy ray-curable pressure-sensitive adhesive) is used as apressure-sensitive adhesive, examples of the radiation-curablepressure-sensitive adhesive (composition) include internalradiation-curable pressure-sensitive adhesives in which a polymer havinga radically reactive carbon-carbon double bond in the polymer side chainor main chain is used as the base polymer, radiation-curablepressure-sensitive adhesives in which a LTV curable monomer component oroligomer component is blended into the pressure-sensitive adhesive, andthe like. Moreover, in the case that the heat-expandablepressure-sensitive adhesive is used as the pressure-sensitive adhesive,there may be mentioned heat-expandable pressure-sensitive adhesivescontaining a pressure-sensitive adhesive and a foaming agent(particularly, heat-expandable microsphere) and the like as theheat-expandable pressure-sensitive adhesive.

In the invention, the pressure-sensitive adhesive layer 32 may containvarious additives (e.g., a tackifying resin, a coloring agent, athickener, an extender, a filler, a plasticizer, an antiaging agent, anantioxidant, a surfactant, a crosslinking agent, etc.) within the rangewhere the advantages of the invention are not impaired.

The crosslinking agent is not particularly restricted and knowncrosslinking agents can be used. Specifically, as the crosslinkingagent, not only isocyanate-based crosslinking agents, epoxy-basedcrosslinking agents, melamine-based crosslinking agents, andperoxide-based crosslinking agents but also urea-based crosslinkingagents, metal alkoxide-based crosslinking agents, metal chelate-basedcrosslinking agents, metal salt-based crosslinking agents,carbodiimide-based crosslinking agents, oxazoline-based crosslinkingagents, aziridine-based crosslinking agents, amine-based crosslinkingagents, and the like may be mentioned, and isocyanate-based crosslinkingagents and epoxy-based crosslinking agents are suitable. Thecrosslinking agent may be employed singly or in a combination of two ormore kinds. Incidentally, the amount of the crosslinking agent is notparticularly restricted.

Examples of the isocyanate-based crosslinking agents include loweraliphatic polyisocyanates such as 1,2-ethylene diisocyanate,1,4-butylene diisocyanate, and 1,6-hexamethylene diisocyanate; alicyclicpolyisocyanates such as cyclopentylene diisocyanate, cyclohexylenediisocyanate, isophorone diisocyanate, hydrogenated tolylenediisocyanate, and hydrogenated xylylene diisocyanate; and aromaticpolyisocyanates such as 2,4-tolylene diisocyanate, 2,6-tolylenediisocyanate, 4,4-diphenylmethane diisocyanate, and xylylenediisocyanate. In addition, a trimethylolpropane/tolylene diisocyanatetrimer adduct [trade name “COLONATE L” manufactured by NipponPolyurethane Industry Co., Ltd.], a trimethylolpropane/hexamethylenediisocyanate trimer adduct [trade name “COLONATE HL” manufactured byNippon Polyurethane Industry Co., Ltd.], and the like are also used.Moreover, examples of the epoxy-based crosslinking agents includeN,N,N′,N′-tetraglycidyl-m-xylenediamine, diglycidylaniline,1,3-bis(N,N-glycidylaminomethyl)cyclohexane, 1,6-hexanediol diglycidylether, neopentyl glycol diglycidyl ether, ethylene glycol diglycidylether, propylene glycol diglycidyl ether, polyethylene glycol diglycidylether, polypropylene glycol diglycidyl ether, sorbitol polyglycidylether, glycerol polyglycidyl ether, pentaerythritol polyglycidyl ether,polyglycerol polyglycidyl ether, sorbitan polyglycidyl ether,trimethylolpropnane polyglycidyl ether, adipic acid diglycidyl ester,o-phthalic acid diglycidyl ester, triglycidyl-tris(2-hydroxyethyl)isocyanurate, resorcin diglycidyl ether, and bisphenol-S-diglycidylether, and also epoxy-based resins having two or more epoxy groups inthe molecule.

In the invention, instead of the use of the crosslinking agent ortogether with the use of the crosslinking agent, it is also possible toperform the crosslinking treatment by irradiation with an electron beamor ultraviolet light.

The pressure-sensitive adhesive layer 32 can be, for example, formed byutilizing a commonly used method including mixing a pressure-sensitiveadhesive and optional solvent and other additives and then shaping themixture into a sheet-like layer. Specifically, the pressure-sensitiveadhesive layer 32 can be, for example, formed by a method includingapplying a mixture containing a pressure-sensitive adhesive and optionalsolvent and other additives on a base material 31, a method includingapplying the above-mentioned mixture on an appropriate separator (suchas a release paper) to form a pressure-sensitive adhesive layer 32 andthen transferring (transcribing) it on a base material 31, or the likemethod.

The thickness of the pressure-sensitive adhesive layer 32 is notparticularly restricted and, for example, is about 5 to 300 μm,preferably 5 to 80 μm, and more preferably 15 to 50 μm. When thethickness of the pressure-sensitive adhesive layer 32 is within theabove-mentioned range, an appropriate pressure-sensitive adhesive forcecan be effectively exhibited. The pressure-sensitive adhesive layer 32may be either a single layer or a multi layer.

According to the invention, the dicing tape-integrated film forsemiconductor back surface 1 can be made to have an antistatic function.Owing to this constitution, the circuit can be prevented from breakingdown due to the generation of electrostatic energy at the time of closeadhesion (adhesion) and at the time of peeling thereof or due tocharging of a workpiece (such as semiconductor wafer) by theelectrostatic energy. Imparting of the antistatic function can beperformed by an appropriate manner such as a method of adding anantistatic agent or a conductive substance to the base material 31, thepressure-sensitive adhesive layer 32, and the film for semiconductorback surface 2 or a method of providing a conductive layer composed of acharge-transfer complex, a metal film, or the like onto the basematerial 31. As these methods, a method in which an impurity ion havinga fear of changing quality of the semiconductor wafer is difficult togenerate is preferable. Examples of the conductive substance (conductivefiller) to be blended for the purpose of imparting conductivity,improving thermal conductivity, and the like include a sphere-shaped, aneedle-shaped, a flake-shaped metal powder of silver, aluminum, gold,copper, nickel, a conductive alloy, or the like; a metal oxide such asalumina; amorphous carbon black, and graphite. However, the film forsemiconductor back surface 2 is preferably non-conductive from theviewpoint of having no electric leakage.

Moreover, the dicing tape-integrated film for semiconductor back surface1 may be formed in a form where it is wound as a roll or may be formedin a form where the sheet (film) is laminated. For example, in the casewhere the film has the form where it is wound as a roll, the film iswound as a roll in a state that the film for semiconductor back surface2 is protected by a separator according to needs, whereby the film canbe prepared as a dicing tape-integrated film for semiconductor backsurface 1 in a state or form where it is wound as a roll. In thisregard, the dicing tape-integrated film for semiconductor back surface 1in the state or form where it is wound as a roll may be constituted bythe base material 31, the pressure-sensitive adhesive layer 32 formed onone surface of the base material 31, the film for semiconductor backsurface 2 formed on the pressure-sensitive adhesive layer 32, and areleasably treated layer (rear surface treated layer) formed on theother surface of the base material 31.

A thickness of the dicing tape-integrated film for semiconductor backsurface 1 (a total thickness of the thickness of the film forsemiconductor back surface 2 and the thickness of the dicing tape 3composed of the base material 31 and the pressure-sensitive adhesivelayer 32) can be, for example, selected within the range of from 11 μmto 300 μm, and it is preferably from 11 μm to 200 μm, more preferablyfrom 15 μm to 200 μm, and further preferably from 15 μm to 100 μm(especially preferably from 20 μm to 80 μm).

In the dicing tape-integrated film for semiconductor back surface 1, aratio of the thickness of the film for semiconductor back surface 2 tothe thickness of the pressure-sensitive adhesive layer 32 in the dicingtape 3 is not particularly restricted, but it can be, for example,properly selected within the range of from 150/5 to 3/100 in terms of aratio of {(thickness of the film for semiconductor back surface2)/(thickness of the pressure-sensitive adhesive layer 32 in the dicingtape 3)}. The ratio of the thickness of the film for semiconductor backsurface 2 to the thickness of the pressure-sensitive adhesive layer 32in the dicing tape 3 is preferably from 100/5 to 3/50, and morepreferably 60/5 to 3/40. When the ratio of the thickness of the film forsemiconductor back surface 2 to the thickness of the pressure-sensitiveadhesive layer 32 in the dicing tape 3 falls within the foregoing range,an appropriate pressure-sensitive adhesive force can be exhibited, andexcellent dicing property and picking-up property can be exhibited.

In the dicing tape-integrated film for semiconductor back surface 1, aratio of the thickness of the film for semiconductor back surface 2 tothe thickness of the dicing tape 3 is not particularly restricted, butit can be, for example, properly selected within the range of from150/50 to 3/500 in terms of a ratio of {(thickness of the film forsemiconductor back surface 2)/(thickness of the dicing tape 3)}. Theratio of the thickness of the film for semiconductor back surface 2 tothe thickness of the dicing tape 3 is preferably from 100/50 to 3/300,and more preferably from 60/50 to 3/150. By regulating the ratio of thethickness of the film for semiconductor back surface 2 to the thicknessof the dicing tape 3 to not more than 3/500, a lowering in thepicking-up property can be suppressed. On the other hand, by regulatingthe ratio of the thickness of the film for semiconductor back surface 2to the thickness of the dicing tape 3 to 150/50 or more, the generationof a lateral residue at dicing or an increase of its amount can besuppressed.

As above, in the dicing tape-integrated film for semiconductor backsurface 1, by regulating the ratio of the thickness of the film forsemiconductor back surface 2 to the thickness of the pressure-sensitiveadhesive layer 32 in the dicing tape 3 or the ratio of the thickness ofthe film for semiconductor back surface 2 to the thickness of the dicingtape 3, a dicing property at the dicing step and a picking-up propertyat the picking-up step can be enhanced. Also, the dicing tape-integratedfilm for semiconductor back surface 1 can be effectively utilized fromthe dicing step of a workpiece such as a semiconductor wafer to the flipchip connection step of a semiconductor element such as a semiconductorchip.

Producing Method of Dicing Tape-Integrated Film for Semiconductor BackSurface

The producing method of the dicing tape-integrated film forsemiconductor back surface of the invention is described while using thedicing tape-integrated film for semiconductor back surface 1 as anexample. First, the base material 31 can be formed by a conventionallyknown film-forming method. Examples of the film-forming method include acalendar film-forming method, a casting method in an organic solvent, aninflation extrusion method in a closely sealed system, a T-die extrusionmethod, a co-extrusion method, and a dry laminating method.

Next, the pressure-sensitive adhesive layer 32 is formed by applying apressure-sensitive adhesive composition onto the base material 31,followed by drying (by crosslinking under heating according to needs).Examples of the application method include roll coating, screen coating,and gravure coating. In this regard, the application of thepressure-sensitive adhesive composition may be performed directly ontothe base material 31 to form the pressure-sensitive adhesive layer 32 onthe base material 31, or the pressure-sensitive adhesive composition maybe applied onto a release paper or the like whose surface has beensubjected to a releasable treatment to form a pressure-sensitiveadhesive layer 32, which is then transferred onto the base material 31to form the pressure-sensitive adhesive layer 32 on the base material31. Thus, a dicing tape 3 is prepared by forming the pressure-sensitiveadhesive layer 32 on the base material 31.

On the other hand, a coating layer is formed by coating a formingmaterial for forming the film for flip chip type semiconductor backsurface 2 on a release paper so as to have a prescribed thickness afterdrying and further drying it under prescribed conditions (in the casewhere thermal curing is required or the like, performing a heatingtreatment to achieve drying, if desired). This coating layer istransferred onto the pressure-sensitive adhesive layer 32, therebyforming the film for flip chip type semiconductor back surface 2 on thepressure-sensitive adhesive layer 32. In this regard, the film for flipchip type semiconductor back surface 2 can also be formed on thepressure-sensitive adhesive layer 32 by coating a forming material forforming the film for flip chip type semiconductor back surface 2directly on the pressure-sensitive adhesive layer 32 and then drying itunder prescribed conditions (in the case where thermal curing isrequired or the like, performing a heating treatment to achieve drying,if desired). There can be thus obtained the dicing tape-integrated filmfor semiconductor back surface 1 according to the invention. In the casewhere thermal curing is performed at the formation of the film forsemiconductor back surface 2, it is important to perform thermal curingto an extent that this is in a partially cured state. However, it ispreferable that the thermal curing is not performed.

The dicing tape-integrated film for semiconductor back surface 1 can besuitably used at the production of a semiconductor device including aflip chip bonding step. Namely, the dicing tape-integrated film forsemiconductor back surface 1 is used at the production of a flipchip-mounted semiconductor device and thus the flip chip-mountedsemiconductor device is produced in a condition or form where the filmfor semiconductor back surface 2 is attached to the back surface of thesemiconductor chip. Therefore, the dicing tape-integrated film forsemiconductor back surface 1 according to the invention can be used fora flip chip-mounted semiconductor device (a semiconductor device in astate or form where the semiconductor chip is fixed to an adherend suchas a substrate by a flip chip bonding method).

Semiconductor Wafer

The workpiece is not particularly restricted as long as it is a known orcommonly used semiconductor wafer and can be appropriately selected andused among semiconductor wafers made of various materials. In theinvention, as the semiconductor wafer, a silicon wafer can be suitableused.

Production Process of Semiconductor Device

The process for producing a semiconductor device of the invention is notparticularly restricted as long as it is a process for producing asemiconductor device using the above-mentioned dicing tape-integratedfilm for semiconductor back surface. For example, a production processincluding the following steps and the like process may be mentioned:

a step (mounting step) of attaching a workpiece onto the film for flipchip type semiconductor back surface of the dicing tape-integrated filmfor semiconductor back surface;

a step (dicing step) of dicing the workpiece to form a semiconductorelement;

a step (picking-up step) of peeling the semiconductor element from thepressure-sensitive adhesive layer of the dicing tape together with thefilm for flip chip type semiconductor back surface; and

-   -   a step (flip chip bonding step) of fixing the semiconductor        element to an adherend by flip chip bonding.

More specifically, as the process for producing a semiconductor device,for example, a semiconductor device can be produced using the dicingtape-integrated film for semiconductor back surface of the invention,after the separator optionally provided on the film for semiconductorback surface is appropriately peeled off, as follows. Hereinafter,referring to FIGS. 2A to 2D, the process is described while using thedicing tape-integrated film for semiconductor back surface 1 as anexample.

FIGS. 2A to 2D are cross-sectional schematic views showing oneembodiment of the process for producing a semiconductor device using thedicing tape-integrated film for semiconductor back surface of theinvention. In FIGS. 2A to 2D, 4 is a workpiece (semiconductor wafer), 5is a semiconductor element (semiconductor chip), 51 is a bump formed atthe circuit face of the semiconductor chip 5, 6 is an adherend, 61 is aconductive material for conjugation adhered to a connecting pad of theadherend 6, and 1, 2, 3, 31, and 32 are respectively a dicingtape-integrated film for semiconductor back surface, a film for flipchip type semiconductor back surface, a dicing tape, a base material,and a pressure-sensitive adhesive layer, as mentioned above.

(Mounting Step)

First, as shown in FIG. 2A, the semiconductor wafer (workpiece) 4 isattached (especially press-bonded) onto the wafer adhesion layer 22 ofthe film for flip chip type semiconductor back surface 2 in the dicingtape-integrated film for semiconductor back surface 1 to fix thesemiconductor wafer by close adhesion (adhesion) and holding (mountingstep). The present step is usually performed while pressing with apressing means such as a pressing roll,

(Dicing Step)

Next, as shown in FIG. 2B, the semiconductor wafer 4 is diced.Consequently, the semiconductor wafer 4 is cut into a prescribed sizeand individualized (is formed into small pieces) to producesemiconductor elements (semiconductor chips) 5. The dicing is performedaccording to a normal method from the circuit face side of thesemiconductor wafer 4, for example. Moreover, the present step canadopt, for example, a cutting method called full-cut that forms a slitreaching the dicing tape-integrated film for semiconductor back surface1. The dicing apparatus used in the present step is not particularlyrestricted, and a conventionally known apparatus can be used. Further,since the semiconductor wafer 4 is close-adhered (adhered) and fixed bythe dicing tape-integrated film for semiconductor back surface 1 havingthe film for semiconductor back surface 2 having a storage elasticmodulus (at 60° C.) of from 0.9 MPa to 15 MPa with an excellent closeadhesiveness, chip crack and chip fly can be suppressed, as well as thedamage of the semiconductor wafer 4 can also be suppressed. In thisregard, when the film for flip chip type semiconductor back surface 2 isformed of a resin composition containing an epoxy resin, generation ofadhesive extrusion from the film for semiconductor back surface 2 issuppressed or prevented at the cut surface even when it is cut bydicing. As a result, re-attachment (blocking) of the cut surfacesthemselves can be suppressed or prevented and thus the picking-up to bementioned below can be furthermore conveniently performed.

In the case where the dicing tape-integrated film for semiconductor backsurface 1 is expanded, the expansion can be performed using aconventionally known expanding apparatus. The expanding apparatus has adoughnut-shaped outer ring capable of pushing the dicing tape-integratedfilm for semiconductor back surface downward through a dicing ring andan inner ring which has a diameter smaller than the outer ring andsupports the dicing tape-integrated film for semiconductor back surface1. Owing to the expanding step, it is possible to prevent the damage ofadjacent semiconductor chips through contact with each other in thepicking-up step to be mentioned below.

(Picking-Up Step)

Picking-up of the semiconductor chip 5 is performed as shown in FIG. 2Cto peel the semiconductor chip 5 together with the film forsemiconductor back surface 2 from the dicing tape 3 in order to collectthe semiconductor chip 5 that is close-adhered (adhered) and fixed tothe dicing tape-integrated film for semiconductor back surface 1. Themethod of picking-up is not particularly restricted, and conventionallyknown various methods can be adopted. For example, there may bementioned a method including pushing up each semiconductor chip 5 fromthe base material 31 side of the dicing tape-integrated film forsemiconductor back surface 1 with a needle and picking-up the pushedsemiconductor chip 5 with a picking-up apparatus. In this regard, theback surface (also referred to as a non-circuit face, anon-electrode-formed face, etc.) of the picked-up semiconductor chip 5is protected with the film for flip chip type semiconductor back surface2.

In the invention, since the storage elastic modulus (at 60° C.) of thefilm for semiconductor back surface 2 is from 0.9 MPa to 15 MPa, thesemiconductor chip 5 can be easily peeled from the dicing tape 3together with the film for semiconductor back surface 2, and picking-upof the semiconductor chip 5 can be performed with an excellentpicking-up property.

(Flip Chip Bonding Step)

The picked-up semiconductor chip 5 is fixed to an adherend such as abase material by a flip chip bonding method (flip chip mounting method).Specifically, the semiconductor chip 5 is fixed to the adherend 6according to a usual manner in a form where the circuit face (alsoreferred to as a front face, circuit pattern-formed face,electrode-formed face, etc.) of the semiconductor chip 5 is opposed tothe adherend 6. For example, the bump 51 formed at the circuit face ofthe semiconductor chip 5 is brought into contact with a conductivematerial 61 (such as solder) attached to a connecting pad of theadherend 6 and the conductive material is melted under pressing, wherebyelectric connection between the semiconductor chip 5 and the adherend 6can be secured and the semiconductor chip 5 can be fixed to the adherend6. In this regard, at the fixing of the semiconductor chip 5 to theadherend 6, it is important that the opposing faces of the semiconductorchip 5 and the adherend 6 and the gap are washed in advance and anencapsulating material (such as an encapsulating resin) is then filledinto the gap.

As the adherend 6, various substrates such as lead frames and circuitboards (such as wiring circuit boards) can be used. The material of thesubstrates is not particularly restricted and there may be mentionedceramic substrates and plastic substrates. Examples of the plasticsubstrates include epoxy substrates, bismaleimide triazine substrates,and polyimide substrates.

In the flip chip bonding, the material of the bump and the conductivematerial is not particularly restricted and examples thereof includesolders (alloys) such as tin-lead-based metal materials,tin-silver-based metal materials, tin-silver-copper-based metalmaterials, tin-zinc-based metal materials, and tin-zinc-bismuth-basedmetal materials, and gold-based metal materials and copper-based metalmaterials.

Incidentally, in the present step, the conductive material is melted toconnect the bump at the circuit face of the semiconductor chip 5 and theconductive material on the surface of the adherend 6. The temperature atthe melting of the conductive material is usually about 260° C. (e.g.,250° C. to 300° C.). The dicing tape-integrated film for semiconductorback surface 1 of the invention can be made to have thermal resistancecapable of enduring the high temperature in the flip chip bonding stepby forming the film for semiconductor back surface 2 with an epoxy resinor the like.

Moreover, the washing liquid to be used at washing the opposing face(electrode-formed face) between the semiconductor chip 5 and theadherend 6 in the flip chip bonding and the gap is not particularlyrestricted and the liquid may be an organic washing liquid or may be anaqueous washing liquid. The film for semiconductor back surface 2 in thedicing tape-integrated film for semiconductor back surface 1 of theinvention has solvent resistance against the washing liquid and hassubstantially no solubility to these washing liquid. Therefore, asmentioned above, various washing liquids can be employed as the washingliquid and the washing can be achieved by any conventional methodwithout requiring any special washing liquid.

In the invention, the encapsulating material to be used at theencapsulation of the gap between the semiconductor chip 5 and theadherend 6 is not particularly restricted as long as the material is aresin having an insulating property (an insulating resin) and may besuitably selected and used among known encapsulating materials such asencapsulating resins. The encapsulating resin is preferably aninsulating resin having elasticity. Examples of the encapsulating resininclude resin compositions containing an epoxy resin. As the epoxyresin, there may be mentioned the epoxy resins exemplified in the above.Furthermore, the encapsulating resin composed of the resin compositioncontaining an epoxy resin may contain a thermosetting resin other thanan epoxy resin (such as a phenol resin) or a thermoplastic resin inaddition to the epoxy resin. Incidentally, a phenol resin can beutilized as a curing agent for the epoxy resin and, as such a phenolresin, there may be mentioned phenol resins exemplified in the above.

In the encapsulation step with the encapsulating resin, theencapsulating resin is usually cured by heating to achieveencapsulation. The curing of the encapsulating resin is usually carriedout at 175° C. for 60 seconds to 90 seconds in many cases. However, inthe invention, without limitation thereto, the curing may be performedat a temperature of 165 to 185° C. for several minutes, for example. Inthis regard, in case that the film for semiconductor back surface 2 isformed of a resin composition containing a thermoplastic resin componentand a thermosetting resin component, the thermosetting resin componentcan be completely or almost completely cured at the curing of thisencapsulating resin.

The distance of the gap between the semiconductor chip 5 and theadherend 6 is generally about 30 μm to 300 μm.

The thus formed semiconductor device can be suitably used as electronicparts or materials thereof.

In the semiconductor device (flip chip-mounted semiconductor device)manufactured using the dicing tape-integrated film for semiconductorback surface 1 of the invention, the film for semiconductor back surface2 is attached to the back surface of the semiconductor element, andtherefore, various making can be applied with excellent visibility. Inparticular, even when the marking method is a laser marking method,marking can be applied with an excellent contrast ratio, and it ispossible to observe various kinds of information (for example, literalinformation and graphical information) applied by laser marking withgood visibility. At the laser marking, a known laser marking apparatuscan be utilized. Moreover, as the laser, it is possible to utilizevarious lasers such as a gas laser, a solid-state laser, and a liquidlaser. Specifically, as the gas laser, any known gas lasers can beutilized without particular limitation but a carbon dioxide laser (CO₂laser) and an excimer laser (ArF laser, KrF laser, XeCl laser, XeFlaser, etc) are suitable. As the solid-state laser, any knownsolid-state lasers can be utilized without particular limitation but aYAG laser (such as Nd:YAG laser) and a YVO₄ laser are suitable.

Since the semiconductor device produced using the dicing tape-integratedfilm for semiconductor back surface of the invention is a semiconductordevice mounted by the flip chip mounting method, the device has athinned and miniaturized shape as compared with a semiconductor devicemounted by a die-bonding mounting method. Thus, the flip chip mountedsemiconductor devices can be suitably employed as various electronicdevices and electronic parts or materials and members thereof.Specifically, as the electronic devices in which the flip chip-mountedsemiconductor devices of the invention are utilized, there may bementioned so-called “mobile phones” and “PHS”, small-sized computers[so-called “PDA” (handheld terminals), so-called “notebook-sizedpersonal computer”, so-called “Net Book (trademark)”, and so-called“wearable computers”, etc.], small-sized electronic devices having aform where a “mobile phone” and a computer are integrated, so-called“Digital Camera (trademark)”, so-called “digital video cameras”,small-sized television sets, small-sized game machines, small-sizeddigital audio players, so-called “electronic notepads”, so-called“electronic dictionary”, electronic device terminals for so-called“electronic books”, mobile electronic devices (portable electronicdevices) such as small-sized digital type watches, and the like.Needless to say, electronic devices (stationary type ones, etc.) otherthan mobile ones, e.g., so-called “desktop personal computers”, thintype television sets, electronic devices for recording and reproduction(hard disk recorders, DVD players, etc.), projectors, micromachines, andthe like may be also mentioned. In addition, electronic parts ormaterials and members for electronic devices and electronic parts arenot particularly restricted and examples thereof include parts forso-called “CPU” and members for various memory devices (so-called“memories”, hard disks, etc.).

EXAMPLES

The following will illustratively describe preferred Examples of theinvention in detail. However, the materials, the mixing amount, and thelike described in these Examples are not intended to limit the scope ofthe invention to only those unless otherwise stated, and they are merelyexplanatory examples. Moreover, part in each example is a weightstandard unless otherwise stated.

Example 1 Preparation of Colored Film for Semiconductor Back Surface

12 parts of an epoxy resin (a trade name: EPIKOTE 1004, manufactured byJER Co., Ltd.), 13 parts of a phenol resin (a trade name: MIREX XLC-4L,manufactured by Mitsui Chemicals, Inc.), 246 parts of spherical silica(a trade name: SO-25R, manufactured by Admatechs Company Limited), 5parts of Dye 1 (a trade name: OIL GREEN 502, manufactured by OrientChemical Industries Co., Ltd.) and 5 parts of Dye 2 (a trade name: OILBLACK BS, manufactured by Orient Chemical Industries Co., Ltd.) based on100 parts of an acrylic acid ester based polymer (a trade name: PARACRONW-197CM, manufactured by Negami Chemical Industrial Co., Ltd.) havingethyl acrylate and methyl methacrylate as main components were dissolvedin methyl ethyl ketone to prepare a solution of a resin compositionhaving a solid concentration of 23.6% by weight.

This resin composition solution was coated on, as a release liner(separator), a releasably treated film constituted of a polyethyleneterephthalate film having a thickness of 50 μm, which had been subjectedto a silicone-releasing treatment, and then dried at 130° C. for 2minutes to prepare a colored film for semiconductor back surface Ahaving an average thickness of 20 μm.

<Preparation of Dicing Tape-Integrated Film for Semiconductor BackSurface>

The foregoing colored film for semiconductor back surface A was attachedonto a pressure-sensitive adhesive layer of a dicing tape (a trade name:V-8-T, manufactured by Nitto Denko Corporation; average thickness ofbase material: 65 μm, average thickness of pressure-sensitive adhesivelayer: 10 μm) by using a hand roller, thereby preparing a dicingtape-integrated film for semiconductor back surface.

In the dicing tape-integrated film for semiconductor back surfaceaccording to this Example 1, a thickness (average thickness) of thecolored film for semiconductor back surface was 20 μm. Also, in thedicing tape (a trade name: V-8-T, manufactured by Nitto DenkoCorporation), an average thickness of the base material was 65 μm; anaverage thickness of the pressure-sensitive adhesive layer was 10 μm;and a total thickness was 75 μm. Accordingly, a ratio of the thicknessof the colored film for semiconductor back surface to the thickness ofthe pressure-sensitive adhesive layer (ratio in average thickness) was20/10; and a ratio of the thickness of the colored film forsemiconductor back surface to the thickness of the dicing tape (ratio inaverage thickness) was 20/75.

Example 2 Preparation of Colored Film for Semiconductor Back Surface

12 parts of an epoxy resin (a trade name: EPIKOTE 1004, manufactured by

JER Co., Ltd.), 13 parts of a phenol resin (a trade name: MIREX XLC-4L,manufactured by Mitsui Chemicals, Inc.), 246 parts of spherical silica(a trade name: SO-25R, manufactured by Admatechs Company Limited), 10parts of Dye 1 (a trade name: OIL GREEN 502, manufactured by OrientChemical Industries Co., Ltd.) and 10 parts of Dye 2 (a trade name: OILBLACK BS, manufactured by Orient Chemical Industries Co., Ltd.) based on100 parts of an acrylic acid ester based polymer (a trade name: PARACRONW-197CM, manufactured by Negami Chemical. Industrial Co., Ltd.) havingethyl acrylate and methyl methacrylate as main components were dissolvedin methyl ethyl ketone to prepare a solution of a resin compositionhaving a solid concentration of 23.6% by weight.

This resin composition solution was coated on, as a release liner(separator), a releasably treated film constituted of a polyethyleneterephthalate film having a thickness of 50 μm, which had been subjectedto a silicone-releasing treatment, and then dried at 130° C. for 2minutes to prepare a colored film for semiconductor back surface Bhaving an average thickness of 20 μm.

<Preparation of Dicing Tape-Integrated Film for Semiconductor BackSurface>

The foregoing colored film for semiconductor back surface B was attachedonto a pressure-sensitive adhesive layer of a dicing tape (a trade name:V-8-T, manufactured by Nitto Denko Corporation; average thickness ofbase material: 65 μm, average thickness of pressure-sensitive adhesivelayer: 10 μm) by using a hand roller, thereby preparing a dicingtape-integrated film for semiconductor back surface.

In the dicing tape-integrated film for semiconductor back surfaceaccording to this Example 2, a thickness (average thickness) of thecolored film for semiconductor back surface was 20 μm. Also, in thedicing tape (a trade name: V-8-T, manufactured by Nitto DenkoCorporation), an average thickness of the base material was 65 μm; anaverage thickness of the pressure-sensitive adhesive layer was 10 μm;and a total thickness was 75 μm. Accordingly, a ratio of the thicknessof the colored film for semiconductor back surface to the thickness ofthe pressure-sensitive adhesive layer (ratio in average thickness) was20/10; and a ratio of the thickness of the colored film forsemiconductor back surface to the thickness of the dicing tape (ratio inaverage thickness) was 20/75.

Example 3 Preparation of Colored Film for Semiconductor Back Surface>

32 parts of an epoxy resin (a trade name: EPIKOTE 1004, manufactured byJER Co., Ltd.), 35 parts of a phenol resin (a trade name: MIREX XLC-4L,manufactured by Mitsui Chemicals, Inc.), 90 parts of spherical silica (atrade name: SO-25R, manufactured by Admatechs Company Limited), 3 partsof Dye 1 (a trade name: OIL GREEN 502, manufactured by Orient ChemicalIndustries Co., Ltd.) and 3 parts of Dye 2 (a trade name: OIL BLACK BS,manufactured by Orient Chemical Industries Co., Ltd.) based on 100 partsof an acrylic acid ester based polymer (a trade name: PARACRON W-197CM,manufactured by Negami Chemical Industrial Co., Ltd.) having ethylacrylate and methyl methacrylate as main components were dissolved inmethyl ethyl ketone to prepare a solution of a resin composition havinga solid concentration of 23.6% by weight.

This resin composition solution was coated on, as a release liner(separator), a releasably treated film constituted of a polyethyleneterephthalate film having a thickness of 50 μm, which had been subjectedto a silicone-releasing treatment, and then dried at 130° C. for 2minutes to prepare a colored film for semiconductor back surface Chaving an average thickness of 20 μm.

<Preparation of Dicing Tape-Integrated Film for Semiconductor BackSurface>

The foregoing colored film for semiconductor back surface C was attachedonto a pressure-sensitive adhesive layer of a dicing tape (a trade name:V-8-T, manufactured by Nitta Denko Corporation; average thickness ofbase material: 65 μm, average thickness of pressure-sensitive adhesivelayer: 10 μm) by using a hand roller, thereby preparing a dicingtape-integrated film for semiconductor back surface.

In the dicing tape-integrated film for semiconductor back surfaceaccording to this Example 3, a thickness (average thickness) of thecolored film for semiconductor back surface was 20 μm. Also, in thedicing tape (a trade name: V-8-T, manufactured by Nitto DenkoCorporation), an average thickness of the base material was 65 μm; anaverage thickness of the pressure-sensitive adhesive layer was 10 μm;and a total thickness was 75 μm. Accordingly, a ratio of the thicknessof the colored film for semiconductor back surface to the thickness ofthe pressure-sensitive adhesive layer (ratio in average thickness) was20/10; and a ratio of the thickness of the colored film forsemiconductor back surface to the thickness of the dicing tape (ratio inaverage thickness) was 20/75.

Example 4 Preparation of Colored Film for Semiconductor Back Surface

113 parts of an epoxy resin (a trade name: EPIKOTE 1004, manufactured byJER Co., Ltd.), 121 parts of a phenol resin (a trade name: MIREX XLC-4L,manufactured by Mitsui Chemicals, Inc.), 223 parts of spherical silica(a trade name: SO-25R, manufactured by Admatechs Company Limited), 5parts of Dye 1 (a trade name: OIL GREEN 502, manufactured by OrientChemical Industries Co., Ltd.) and 5 parts of Dye 2 (a trade name: OILBLACK BS, manufactured by Orient Chemical Industries Co., Ltd.) based on100 parts of an acrylic acid ester based polymer (a trade name: PARACRONW-197CM, manufactured by Negami Chemical Industrial Co., Ltd.) havingethyl acrylate and methyl methacrylate as main components were dissolvedin methyl ethyl ketone to prepare a solution of a resin compositionhaving a solid concentration of 23.6% by weight.

This resin composition solution was coated on, as a release liner(separator), a releasably treated film constituted of a polyethyleneterephthalate film having a thickness of 50 μm, which had been subjectedto a silicone-releasing treatment, and then dried at 130° C. for 2minutes to prepare a colored film for semiconductor back surface Dhaving an average thickness of 20 μm.

<Preparation of Dicing Tape-Integrated Film for Semiconductor BackSurface>

The foregoing colored film for semiconductor back surface D was attachedonto a pressure-sensitive adhesive layer of a dicing tape (a trade name:V-8-T, manufactured by Nitto Denko Corporation; average thickness ofbase material: 65 μm, average thickness of pressure-sensitive adhesivelayer: 10 μm) by using a hand roller, thereby preparing a dicingtape-integrated film for semiconductor back surface.

In the dicing tape-integrated film for semiconductor back surfaceaccording to this Example 4, a thickness (average thickness) of thecolored film for semiconductor back surface was 20 μm. Also, in thedicing tape (a trade name: V-8-T, manufactured by Nitto DenkoCorporation), an average thickness of the base material was 65 μm; anaverage thickness of the pressure-sensitive adhesive layer was 10 μm;and a total thickness was 75 μm. Accordingly, a ratio of the thicknessof the colored film for semiconductor back surface to the thickness ofthe pressure-sensitive adhesive layer (ratio in average thickness) was20/10; and a ratio of the thickness of the colored film forsemiconductor back surface to the thickness of the dicing tape (ratio inaverage thickness) was 20/75.

Comparative Example 1 Preparation of Colored Film for Semiconductor BackSurface>

113 parts of an epoxy resin (a trade name: EPIKOTE 1004, manufactured byJER Co., Ltd.), 121 parts of a phenol resin (a trade name: MIREX XLC-4L,manufactured by Mitsui Chemicals, Inc.), 3,006 parts of spherical silica(a trade name: SO-25R, manufactured by Admatechs Company Limited), 5parts of Dye 1 (a trade name: OIL GREEN 502, manufactured by OrientChemical Industries Co., Ltd.) and 5 parts of Dye 2 (a trade name: OILBLACK BS, manufactured by Orient Chemical Industries Co., Ltd.) based on100 parts of an acrylic acid ester based polymer (a trade name: PARACRONW-197CM, manufactured by Negami Chemical Industrial Co., Ltd.) havingethyl acrylate and methyl methacrylate as main components were dissolvedin methyl ethyl ketone to prepare a solution of a resin compositionhaving a solid concentration of 23.6% by weight.

This resin composition solution was coated on, as a release liner(separator), a releasably treated film constituted of a polyethyleneterephthalate film having a thickness of 50 μm, which had been subjectedto a silicone-releasing treatment, and then dried at 130° C. for 2minutes to prepare a colored film for semiconductor back surface Ehaving an average thickness of 20 μm.

<Preparation of Dicing Tape-Integrated Film for Semiconductor BackSurface>

The foregoing colored film for semiconductor back surface E was attachedonto a pressure-sensitive adhesive layer of a dicing tape (a trade name:V-8-T, manufactured by Nitto Denko Corporation; average thickness ofbase material: 65 μm, average thickness of pressure-sensitive adhesivelayer: 10 μm) by using a hand roller, thereby preparing a dicingtape-integrated film for semiconductor back surface.

In the dicing tape-integrated film for semiconductor back surfaceaccording to this Comparative Example 1, a thickness (average thickness)of the colored film for semiconductor back surface was 20 μm. Also, inthe dicing tape (a trade name: V-8-T, manufactured by Nitto DenkoCorporation), an average thickness of the base material was 65 μm; anaverage thickness of the pressure-sensitive adhesive layer was 10 μm;and a total thickness was 75 μm. Accordingly, a ratio of the thicknessof the colored film for semiconductor back surface to the thickness ofthe pressure-sensitive adhesive layer (ratio in average thickness) was20/10; and a ratio of the thickness of the colored film forsemiconductor back surface to the thickness of the dicing tape (ratio inaverage thickness) was 20/75.

Comparative Example 2 Preparation of Colored Film for Semiconductor BackSurface>

273 parts of an epoxy resin (a trade name: EPIKOTE 828, manufactured byJER Co., Ltd.), 293 parts of a phenol resin (a trade name: MIREX XLC-4L,manufactured by Mitsui Chemicals, Inc.), 246 parts of spherical silica(a trade name: SO-25R, manufactured by Admatechs Company Limited), 5parts of Dye 1 (a trade name: OIL GREEN 502, manufactured by OrientChemical Industries Co., Ltd.) and 5 parts of Dye 2 (a trade name: OILBLACK BS, manufactured by Orient Chemical Industries Co., Ltd.) based on100 parts of an acrylic acid ester based polymer (a trade name: PARACRONW-197CM, manufactured by Negami Chemical Industrial Co., Ltd.) havingethyl acrylate and methyl methacrylate as main components were dissolvedin methyl ethyl ketone to prepare a solution of a resin compositionhaving a solid concentration of 23.6% by weight.

This resin composition solution was coated on, as a release liner(separator), a releasably treated film constituted of a polyethyleneterephthalate film having a thickness of 50 μm, which had been subjectedto a silicone-releasing treatment, and then dried at 130° C. for 2minutes to prepare a colored film for semiconductor back surface Fhaving an average thickness of 20 μm.

<Preparation of Dicing Tape-Integrated Film for Semiconductor BackSurface>

The foregoing colored film for semiconductor back surface F was attachedonto a pressure-sensitive adhesive layer of a dicing tape (a trade name:V-8-T, manufactured by Nitto Denko Corporation; average thickness ofbase material: 65 μm, average thickness of pressure-sensitive adhesivelayer: 10 μm) by using a hand roller, thereby preparing a dicingtape-integrated film for semiconductor back surface.

In the dicing tape-integrated film for semiconductor back surfaceaccording to this Comparative Example 2, a thickness (average thickness)of the colored film for semiconductor back surface was 20 μm. Also, inthe dicing tape (a trade name: V-8-T, manufactured by Nitto DenkoCorporation), an average thickness of the base material was 65 μm; anaverage thickness of the pressure-sensitive adhesive layer is 10 μm; anda total thickness is 75 μm. Accordingly, a ratio of the thickness of thecolored film for semiconductor back surface to the thickness of thepressure-sensitive adhesive layer (ratio in average thickness) was20/10; and a ratio of the thickness of the colored film forsemiconductor back surface to the thickness of the dicing tape (ratio inaverage thickness) was 20/75.

(Measurement of Physical Properties of Colored Film for SemiconductorBack Surface)

With respect to each of the colored film for semiconductor back surfacesin the dicing tape-integrated film for semiconductor back surfacesprepared in Examples 1 to 4 and Comparative Examples 1 to 2, a visiblelight transmittance (%), a moisture absorbance (% by weight) and aweight decrease ratio (% by weight) were measured, respectively in thefollowing manners. The results of the measurement are shown in thefollowing Table 1.

<Measuring Method of Visible Light Transmittance>

Each of the colored film for semiconductor back surfaces A to F preparedin Examples 1 to 4 and Comparative Examples 1 to 2 (average thickness:20 μm) was irradiated with visible light using “ABSORPTION SPECTROPHOTOMETER” (a trade name, manufactured by Shimadzu Corporation). Awavelength of the visible light was regulated to from 400 nm to 800 μm.A light intensity of the visible light which had transmitted through thecolored film for semiconductor back surface 2 by this irradiation wasmeasured and calculated according to the following expression,

Visible light transmittance (%)=[(Light intensity of visible light aftertransmitting through the colored film for semiconductor backsurface)/(Initial light intensity of visible light)]×100

<Measuring Method of Moisture Absorbance>

Each of the colored film for semiconductor back surfaces A to F preparedin Examples 1 to 4 and Comparative Examples 1 to 2 was allowed to standin a constant-temperature and constant-humidity chamber at a temperatureof 85° C. and a humidity of 85% RH for 168 hours. A weight before andafter standing was measured, and a moisture absorbance (% by weight) wascalculated according to the following expression.

Moisture absorbance (% by weight)=[{(Weight after allowing the coloredfilm for semiconductor back surface to stand)−(Weight before allowingthe colored film for semiconductor back surface to stand)}/(Weightbefore allowing the colored film for semiconductor back surface tostand)]×100

<Measuring Method of Weight Decrease Ratio>

Each of the colored film for semiconductor back surfaces A to F preparedin Examples 1 to 4 and Comparative Examples 1 to 2 was allowed to standin a drying machine at a temperature of 250° C. for 1 hour. A weightbefore and after standing was measured, and a weight decrease ratio (%by weight) was calculated according to the following expression.

Weight decrease ratio (% by weight)=[{(Weight before allowing thecolored film for semiconductor back surface to stand)−(Weight afterallowing the colored film for semiconductor back surface tostand)}/(Weight before allowing the colored film for semiconductor backsurface to stand)]×100

TABLE 1 Film for semiconductor Visible light Moisture absorbance Weightdecrease ratio back surface transmittance (%) (% by weight) (% byweight) Example 1 Colored film for 0 0.3 1.0 semiconductor back surfaceA Example 2 Colored film for 0 0.3 1.1 semiconductor back surface BExample 3 Colored film for 0 0.3 1.3 semiconductor back surface CExample 4 Colored film for 0 0.3 0.9 semiconductor back surface DComparative Colored film for 0 0.2 0.5 Example 1 semiconductor backsurface E Comparative Colored film for 0 0.4 1.5 Example 2 semiconductorback surface F

(Evaluation)

With respect to each of the dicing tape-integrated film forsemiconductor back surfaces prepared in Examples 1 to 4 and ComparativeExamples 1 to 2, an adhesive force of the colored film for semiconductorback surface to the semiconductor wafer, a dicing property, a picking-upproperty, a flip chip bonding property, a marking property of thesemiconductor wafer back surface and an appearance property of thesemiconductor wafer back surface were evaluated or measured by thefollowing evaluating or measuring methods. The results of the evaluationor measurement are shown in Table 2.

<Measuring Method of Storage Elastic Modulus of Colored Film forSemiconductor Back Surface>

The storage elastic modulus (tensile storage elastic modulus) of thecolored film for semiconductor back surface was determined by preparinga colored film for semiconductor back surface without being laminated ona dicing tape and measuring a storage elastic modulus in a tensile modeunder conditions of a sample width of 10 mm, a sample length of 22.5 mm,a sample thickness of 0.2 mm, a frequency of 1 Hz and a temperatureelevating rate of 10° C./min under a nitrogen atmosphere at a prescribedtemperature (60° C.) using a dynamic viscoelasticity measuring apparatus“Solid Analyzer RS A2”, manufactured by Rheometrics Co., Ltd. and wasregarded as a value of obtained tensile storage elastic modulus E′.

<Measuring Method of Adhesive Force of Colored Film for SemiconductorBack Surface to Semiconductor Wafer>

A peel force of the colored film for semiconductor back surface to thesemiconductor wafer is determined as follows. That is, a silicon waferas a semiconductor wafer is placed on a hot plate, and a colored filmfor semiconductor back surface having a length of 150 mm and a width of10 mm, whose back surface is reinforced with a pressure-sensitive tape(a trade name: BT315, manufactured by Nitto Denko Corporation), wasattached thereon at a prescribed temperature (50° C.) by reciprocating aroller of 2 kg at 50° C. once. Thereafter, the laminate is allowed tostand on a hot plate (50° C.) for 2 minutes and then allowed to stand atordinary temperature (about 23° C.) for 20 minutes. After standing, theback surface-reinforced colored film for semiconductor back surface ispeeled (peeled at an interface between the colored film forsemiconductor back surface and the semiconductor wafer) at a temperatureof 23° C. under conditions of a peel angle of 180° and a tensile rate of300 mm/min by using a peel tester (a trade name: AUTOGRAPH AGS-J,manufactured by Shimadzu Corporation). A maximum load of the load at thepeeling time (a maximum value of the load from which a peak top at thebeginning of measurement has been eliminated) is measured, and anadhesive force (N/10 nun-width) of the colored film for semiconductorback surface is determined while regarding this maximum load as anadhesive force between the colored film for semiconductor back surfaceand the semiconductor wafer (adhesive force of the colored film forsemiconductor back surface to the semiconductor wafer).

<Evaluation Method of Dicing Property and Picking-Up Property>

By using each of the dicing tape-integrated film for semiconductor backsurfaces of Examples 1 to 4 and Comparative Examples 1 to 2, the dicingproperty was evaluated by actually dicing a semiconductor wafer, andthereafter, a peeling property was evaluated, thereby evaluating adicing performance and a picking-up performance of the dicingtape-integrated film for semiconductor back surface.

A semiconductor wafer (diameter: 8 inches, thickness: 0.6 mm; a siliconmirror wafer) was subjected to a back surface polishing treatment, and amirror wafer having a thickness of 0.2 mm was used as a workpiece. Afterthe separator was peeled from the dicing tape-integrated film forsemiconductor back surface, the mirror wafer (workpiece) was attachedonto the colored film for semiconductor back surface by rollerpress-bonding at 60° C., and dicing was further performed. Herein, thedicing was performed as full cut so as to be a chip size of 10 mm insquare. In this regard, conditions for semiconductor wafer grinding,attaching conditions and dicing conditions are as follows.

(Conditions for Semiconductor Wafer Grinding)

Grinding apparatus: trade name “DFG-8560” manufactured by DISCOCorporation Semiconductor wafer: 8 inch diameter (back surface wasground so as to be until a thickness of 0.2 mm from a thickness of 0.6mm)

(Attaching Conditions)

Attaching apparatus: trade name “MA-3000II” manufactured by Nitto SeikiCo., Ltd.Attaching speed: 10 mm/minAttaching pressure: 0.15 MPaStage temperature at the time of attaching: 60° C.

(Dicing Conditions)

Dicing apparatus: trade name “DFD-6361” manufactured by DISCOCorporationDicing ring: “2-8-1” (manufactured by DISCO Corporation)Dicing speed: 30 mm/secDicing blade:

-   -   Z1; “203O-SE 27HCDD” manufactured by DISCO Corporation    -   Z2; “203O-SE 27HCBB” manufactured by DISCO Corporation        Dicing blade rotation speed:    -   Z1; 40,000 r/min    -   Z2; 45,000 r/min        Cutting method: step cutting        Wafer chip size: 10.0 mm square

In the dicing, it was confirmed whether the mirror wafer (workpiece) wasfirmly held on the dicing tape-integrated film for semiconductor backsurface without peeling to effect the dicing satisfactory or not. Thecase where the dicing was well performed was ranked “Good” and the casewhere the dicing was not well performed was ranked “Bad”, thus thedicing ability being evaluated.

Next, the semiconductor chip obtained by dicing was peeled from thepressure-sensitive adhesive layer of the dicing tape together with thefilm for flip chip type semiconductor back surface by pushing up thesemiconductor chip from the dicing tape side of the dicingtape-integrated film for semiconductor back surface with a needle,whereby the semiconductor chip in a state where the back surface hadbeen protected with the film for semiconductor back surface was pickedup. The picking-up ratio (%) of the chips (400 pieces in total) on thisoccasion was determined to evaluate the picking-up property. Therefore,the picking-up property is better when the picking-up ratio is closer to100%.

Here, the picking-up conditions are as follows.

(Picking-Up Conditions for Semiconductor Wafer)

Picking-up apparatus: trade name “SPA-300” manufactured by Shinkawa Co.,Ltd.Number of picking-up needles: 9 needlesPushing-up speed of needle: 20 mm/sPushing-up distance of needle: 500 μmPicking-up time: 1 secondDicing tape-expanding amount: 3 mm

<Evaluation Method for Flip Chip Bonding Property>

On the semiconductor chip according to each of the Examples andComparative Examples obtained by the above-mentioned <Evaluation methodof dicing properties/picking-up property>using the dicingtape-integrated film for semiconductor back surface according to each ofthe Examples and Comparative Examples, a bump formed at the circuit faceof the semiconductor chip was brought into contact with a conductivematerial (solder) attached to a connecting pad of the circuit board in aform where the surface (circuit face) of the semiconductor chip wasopposed to the surface of the circuit board possessing a wiringcorresponding to the circuit face, and the conductive material wasmelted under pressure by raising the temperature to 260° C. and thencooled to room temperature, whereby the semiconductor chip was fixed tothe circuit board to manufacture a semiconductor device. The flip chipbonding property on this occasion was evaluated according to thefollowing evaluation standard.

(Evaluation Standard for Flip Chip Bonding Property)

Good: Mounting could be achieved by the flip chip bonding method with notrouble;Bad: Mounting could not be achieved by the flip chip bonding method.

<Evaluation Method for Marking Property of Wafer Back Surface>

Laser marking was applied on the back surface of the semiconductor chip(i.e., the surface of the colored film for semiconductor back surface)in the semiconductor device obtained by the above-mentioned <Evaluationmethod for flip chip bonding property> with using YAG laser. On theinformation obtained by the laser marking (bar-code information), thelaser marking property of the semiconductor device obtained using thedicing tape-integrated film for semiconductor back surface according toeach of the Examples and Comparative Examples was evaluated according tothe following evaluation standard.

(Evaluation Standard for Laser Marking Property)

Good: The number of persons who judged the information obtained by thelaser marking satisfactorily visible was 8 persons or more amongrandomly selected 10 adult persons;Bad: The number of persons who judged the information obtained by thelaser marking satisfactorily visible was 7 persons or less amongrandomly selected 10 adult persons.

<Evaluation Method for Appearance Property of Wafer Back Surface>

On the semiconductor chip according to each of the Examples andComparative Examples obtained by the above-mentioned <Evaluation methodof dicing property/picking-up property>using the dicing tape-integratedfilm for semiconductor back surface according to each of the Examplesand Comparative Examples, the appearance property of the back surface ofthe semiconductor chip was visually evaluated according to the followingevaluation standard.

(Evaluation Standard for Appearance Properties>

Good: No peeling (lifting) was observed between the back surface of thewafer (silicon wafer) and the film for semiconductor back surface in thesemiconductor chip;Bad: Peeling (lifting) was observed between the back surface of thewafer (silicon wafer) and the film for semiconductor back surface in thesemiconductor chip.

TABLE 2 Thermoplastic Adhesive force Picking-up Flip chip Laser resin(N/10 mm- Dicing property bonding marking Appearance (wt %) width)property (%) property property property Example 1 1.23 8.3 or more Good100 Good Good Good Example 2 1.34 8.3 or more Good 100 Good Good GoodExample 3 0.9 4.3 Good 100 Good Good Good Example 4 4.2 8.3 or more Good100 Good Good Good Comparative 16.5 0   Bad Bad Bad Bad Bad Example 1Comparative 0.078 8.3 or more Good Bad Bad Bad Bad Example 2

It can be seen from Table 2 that the dicing tape-integrated films forsemiconductor back surface according to Examples 1 to 4 have a functionas a dicing tape and functions as a colored film for semiconductor backsurface on excellent levels.

In the dicing tape-integrated film for semiconductor back surface of theinvention, not only the dicing tape and the film for semiconductor backsurface are formed in an integrated form, but the storage elasticmodulus (at 60° C.) of the film for semiconductor back surface is from0.9 MPa to 15 MPa. Therefore, the dicing tape-integrated film forsemiconductor back surface of the invention can be utilized from adicing step of a semiconductor wafer to a flip chip bonding step of asemiconductor chip. That is the dicing tape-integrated film forsemiconductor back surface of the invention can be suitably used as adicing tape-integrated film for semiconductor back surface provided withboth functions as a dicing tape and a film for semiconductor backsurface at manufacturing a semiconductor device by a flip chip bondingmethod.

While the present invention has been described in detail and withreference to specific embodiments thereof, it will be apparent to oneskilled in the art that various changes and modifications can be madetherein without departing from the scope thereof.

This application is based on Japanese patent application No. 2009-142231filed Jun. 15, 2009 and Japanese patent application No. 2010-103964filed Apr. 28, 2010, the entire contents thereof being herebyincorporated by reference.

1. A dicing tape-integrated film for semiconductor back surface,comprising: a dicing tape including a base material and apressure-sensitive adhesive layer provided on the base material; and afilm for flip chip type semiconductor back surface provided on thepressure-sensitive adhesive layer, wherein the film for flip chip typesemiconductor back surface has a storage elastic modulus (at 60° C.) offrom 0.9 MPa to 15 MPa.
 2. The dicing tape-integrated film forsemiconductor back surface according to claim 1, wherein the film forflip chip type semiconductor back surface contains a coloring agentadded thereto.
 3. The dicing tape-integrated film for semiconductor backsurface according to claim 1, which is used at the time of flip chipbonding.
 4. The dicing tape-integrated film for semiconductor backsurface according to claim 2, which is used at the time of flip chipbonding.
 5. A process for producing a semiconductor device using thedicing tape-integrated film for semiconductor back surface according toclaim 1, the process comprising: attaching a workpiece onto the film forflip chip type semiconductor back surface of the dicing tape-integratedfilm for semiconductor back surface, dicing the workpiece to form achip-shaped workpiece, peeling the chip-shaped workpiece from thepressure-sensitive adhesive layer of the dicing tape together with thefilm for flip chip type back surface, and flip chip connecting thechip-shaped workpiece onto an adherend.
 6. A flip chip-mountedsemiconductor device, which is manufactured by the process according toclaim 5.